Matrix power amplifier

ABSTRACT

A power amplifier includes a two-dimensional matrix of N×M active cells formed by stacking main terminals of multiple active cells in series. The stacks are coupled in parallel to form the two-dimensional matrix. The power amplifier includes a driver structure to coordinate the driving of the active cells so that the effective output power of the two-dimensional matrix is approximately N×M the output power of each of the active cells.

BACKGROUND

This invention relates to power amplifiers, for example, the poweramplifiers that include at least a two-dimensional matrix of transistorsand can be tuned to match the impedance of an antenna or other load.

Transistors are devices that can amplify a control signal that is inputinto a control terminal. Transistors can be made from a variety ofdifferent materials, can have a variety of different geometries, and canoperate according to a variety of different physical mechanisms. Examplematerials include silicon, gallium arsenide, gallium nitride, andsilicon carbide. These and other materials can be used to form devicessuch as bipolar transistors and field effect transistors that includeeither insulated control terminals (e.g., IGBTs, MOSFETs, HEMT's orHFET5) or that include control terminals made from PN junctions (e.g.,BJTs or JFETs).

Regardless of the materials and device structures, individualtransistors all have fundamental limits on their safe operationalranges. For example, if an excessively large voltage is applied acrossthe main terminals, then dielectric breakdown may occur and thetransistor may be damaged or destroyed. As another example, if anexcessively large current flows between the main terminals, then thetransistor may also be damaged or destroyed.

Although the operational ranges of individual transistors may besuitable for some applications, they may be insufficient to meet therequirements of others. For example, some applications may requirevoltages in excess of the breakdown voltage or currents in excess of thepeak currents of even well-designed transistors. Examples of suchapplications include driving antennas for the transmission of, e.g.,radar signals and communication signals (e.g., for satellitecommunication and terrestrial broadcasts in both military and civiliancontexts).

In such applications, individual transistors can be grouped in order tohandle large voltages and/or currents as a group. For example,individual transistors can be stacked (or “series-stacked”) so thatalmost all of the current that flows through the main terminals of thefirst transistor in the stack also flows through the main terminals ofsubsequent transistor(s) in the stack. Each of the transistors in thestack supports some portion of the voltage that drives this current. Thetotal voltage supported across the stack of transistors can be in excessof the breakdown voltage of the individual transistors.

As another example, individual transistors can be paralleled so thatessentially the same voltage is coupled across the main terminals ofmultiple transistors. When multiple transistors are conductive, the netcurrent flow through the group can exceed the peak current of theindividual constituent transistors.

In idealized small-signal models, power transfer from a signal source toa load can be improved by matching the output impedance of the source(also known as “the source impedance”) to the impedance of the load. Insuch models, the maximum possible power is transferred when theimpedance of the load is exactly equal to the complex conjugate of thesource impedance over an infinite range of frequencies.

However, in real-world, large-signal applications, the “sourceimpedance” is not properly defined or, strictly speaking, does not existdue to lack of linearity or the missing superposition law. Nevertheless,theory and practice show that a sufficiently large portion of the poweris transferred (i.e., the power-added efficiency (PAE) is sufficientlyhigh) for certain values of the load impedance. The term “optimum loadimpedance” is used herein to characterize the circumstances where asufficiently large portion of the power is transferred over a range ofoperational frequencies of interest.

SUMMARY

Power amplifiers that include at least a two-dimensional matrix ofactive cells are described. The active cells are generally individualtransistors. The two-dimensional matrix of transistors is formed bystacks of multiple active cells that are coupled in parallel, henceforming a “two-dimensional matrix.” Each stack in the matrix can supporta relatively large voltage while conducting a given current. Each stackcan thus be considered a source that has its own—relativelylarge—optimum load impedance. However, since the stacks are coupled inparallel, the two-dimensional matrix has a net impedance that is afraction of the impedance of the constituent stacks. Thus, the impedanceof the matrix as a whole can be tailored to match the impedance of aload and transfer a relatively large portion of the power over a rangeof operational frequencies of interest.

In more detail, the impedance of an input port (“Z_(in_port)”) and anoutput port (“Z_(out_port)”)—and the impedance of the correspondingpower distribution and collection rails—of a matrix power amplifier islargely independent of the number of active cells in the amplifier.Instead, Z_(in_port) and Z_(out_port) are only dependent upon the ratioof the number of rows N and the number of columns M, as well as theinput and output impedance of the individual active cells (i.e.,“Z_(cell_in)” and “Z_(cell_out),” respectively). In particular,

$\begin{matrix}{Z_{{in}\_ {port}} = {\frac{N}{M}*Z_{{cell}\_ {in}}}} & {{Equation}\mspace{14mu} 1} \\{and} & \; \\{z_{{out}\_ {port}} = {\frac{N}{M}*Z_{{cell}\_ {out}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

In general, Z_(cell_in) and Z_(cell_out) are tailorable over arelatively limited range (e.g., by tailoring the active cell devicegeometry and other properties). However, the ratio of the number of rowsto the number of columns (N/M) in a matrix power amplifier is mucheasier to adjust. Thus, by controlling all of these parameters, matrixpower amplifiers of arbitrary input and output port impedances can beachieved.

The bandwidth of a matrix power amplifier is limited only by thebandwidth of the individual cells and the matching of the complex-valuedinput/output port impedances Z_(in_port) and Z_(out_port) to the(real-valued) system impedance Z₀. Since the ratio N/M is notconstrained to any particular number of active cells (e.g., a 10×10matrix of 100 active cells has the same N/M ratio as a 4×4 matrix of 16active cells), the achievable output power is not limited by the numberof active cells. Rather, the achievable output power is limited by thereal-world considerations described above (including, e.g., residualmagnitude and phase errors, finite losses of the power matching networkswithin the matrix power amplifier). Absent such non-idealities, thetheoretical output power would increase in proportion to the matrix sizeN*M.

The matrix power amplifiers described herein can use active or passiveinput driver structures that individually and synchronously drive theactive cells of the two-dimensional matrix power amplifier. In an idealtwo-dimensional matrix, each of the active cells would receive aseparate but identical drive signal at its respective control terminal.Further, no current would be lost in driving the control terminals.Although such ideal behavior is impossible to achieve due to a varietyof physical realities (e.g., slight mismatches in the physicalcharacteristics of components, parasitic capacitances and inductances,etc.), the driving of the active cells in the power amplifiers describedherein is sufficiently synchronous to provide a total power output thatis approximately N*M times the effective output power of a single cellin the matrix, where N is the number of rows in the matrix and M is thenumber of columns.

In some implementations, the power amplifiers described herein caninclude an “active source follower return.” In particular, an activesource follower return can be implemented by a pair of matrix amplifiersthat are driven by drive signals of opposite polarity. The two matrixamplifiers are assembled in a complementary or quasi-complementarytopology to respectively “push up” and “pull down” the output. In someimplementations, active source follower returns can be implemented as a(monolithic) microwave integrated circuit (MIC) device. In such cases,the active source follower return can output high voltage and currentsignals while retaining the other advantages of integrated circuitdevices.

In some implementations, the control terminals of the active cells ofthe matrix power amplifiers are coupled together in rows, in columns, orin both rows and columns using transmission lines that are suited fortransmitting microwave or millimeter-wave frequency drive signals and(nearly) synchronously driving the active cells. In general, thecharacteristic impedance of the transmission lines can be selected to be50 Ω. However, in some circumstances (e.g., large transistor cells), itmay be advantageous to select a lower impedance value (e.g., 20 Ω oreven 10 Ω) for input and output matching of the active cells within thematrix amplifier, especially if high absolute or relative bandwidths arerequired. As another example, the lengths of the transmission lines arenot zero (i.e., the control terminals of the active cells are notdirectly coupled) but rather the lengths can be selected so that thedistribution of drive signals to different control terminals is nearlyidentical and nearly synchronous driving of the active cells can beachieved. By having non-zero transmission line lengths, neighboringactive cells can be physically separated from one another and thethermal coupling between active cells sufficiently reduced to allow evenrelatively large powers to be amplified.

The matrix power amplifiers described herein all amplify an RF signaloutput by an RF source. The RF signal can be coupled into the matrixpower amplifiers in a variety of different ways. For example, in someimplementations, the RF signal can be coupled:

-   -   directly into the active cells in the bottom row of the matrix        power amplifier (i.e., without an intervening active driver (but        optionally with a passive impedance matching network) between        the RF source and the active cells, and    -   into other active cells of the matrix power amplifier by way of        an intervening active driver at the base of a column driver.

-   Examples of such matrix power amplifiers are shown, e.g., in FIGS.    9, 10, 11. In these implementations, if one assumes that the power    output from all the active cells in the bottom row (i.e.,    P_(out,Bc)) is identical (as would be the case if those active cells    and power distribution to those cells were identical), then the    power output of the matrix power amplifier (i.e., P_(out)) is    approximately equal to the product of the power output of the    individual cells in the bottom row and the total number of active    cells, or

P _(out) =N*M*P _(out,Bc)   Equation 3.

Further, the gain of each active cell (i.e., GBc) is given by the poweroutput of that active cell (i.e., P_(out,BC))for a given power inputinto that active cell. Assuming that power is divided evenly between theactive cells in the bottom row and the active driver at the base of acolumn driver, then the power input into each active cell in the bottomrow is given by the total power input (i.e., P_(in)) divided by the sumof the number of columns (i.e., M)+1 to account for the active driver atthe base of a column driver, or

P _(in)=(M+1)*P _(out,Bc) /G _(BC)   Equation 4.

Thus, the total power gain of the matrix amplifier (i.e., G_(2D)) isgiven by:

G _(2D) =P _(out) /P _(in) =N*M/(M+1)*G _(BC)   Equation 5.

As another example, in some implementations, the RF signal can becoupled:

-   -   directly into the active cells in the bottom row of the matrix        power amplifier (i.e., without an intervening active driver (but        optionally with a passive impedance matching network) between        the RF source and the active cells), and    -   directly into other active cells of the matrix power amplifier        (i.e., without an intervening active driver (but optionally with        a passive impedance matching network) between the RF source and        the active cells).

-   Examples of such matrix power amplifiers are shown, e.g., in FIGS.    4-8. In these implementations, the power output of the matrix power    amplifier and the total power gain of the matrix amplifier is the    same as given in Equations 3, 4, 5.

However, in these implementations, the effective power gain of thematrix amplifier and the maximum output power of the individual poweractive cells in the matrix decrease with increasing frequency becausethe input power needed for each cell cannot be transferred to theoutput.

As another example, in some implementations, the RF signal can becoupled:

-   -   into all active cells—including those in the bottom row—of the        matrix power amplifier by way of an intervening active driver.

-   An example of such a matrix power amplifier is shown, e.g., in    FIG. 3. In such matrix power amplifiers, the power input into each    active cell in the matrix power amplifier is given by the total    power input (i.e., P_(in)) divided by the total number of active    cells. In other words, the power input into each active cell is the    total power input (i.e., P_(in)) divided by the matrix size N*M.    Thus, assuming identical active cells,

P _(in)=(N*M)*P _(out,Bc) /G _(BC)   Equation 6.

Thus, the total power gain of the matrix amplifier (i.e., G_(2D)) isgiven by:

G _(2D) =P _(out) /P _(in) =G _(BC)   Equation 7.

Such matrix power amplifiers do not have any gain multiplicationresulting from the matrix dimensions.

As yet another example, in some implementations, the RF signal can becoupled:

-   -   into a single bottom driver cell of a column driver the matrix        power amplifier. The active cells in the bottom row and the        upper rows of the matrix power amplifier can be driven by a        chain or stack of active baluns or differential amplifiers. Each        active device can drive all the active cells in a corresponding        row.

-   Examples of such a matrix power amplifier is shown, e.g., in    FIG. 12. In such matrix power amplifiers, the entire power input    into matrix power amplifier is provided to the bottom active cell.    Thus,

P _(in) =P _(out,BC) /G _(SBC)   Equation 8

and the total power gain of the matrix amplifier (i.e., G_(2D)) is givenby:

G _(2D) =P _(out) /P _(in) 32 N*M*G _(SBC)   Equation 9.

This is the theoretical ideal case of an ideal 2D matrix power amplifierwith an active driver column where only the bottom cell of this driveris driven by the RF input source.

In light thereof, various aspects of a matrix power amplifier can bedescribed. In a first aspect, a power amplifier includes an amplifierinput and an amplifier output, a plurality of N times M active cells,wherein N and M are both≥2 and the active cells are wired as a M×Nmatrix, and at least one driver structure to drive the active cells. Oneof a), b), or c) applies, wherein when a) applies, the matrix columnseach include N active cells coupled in series and driven as a stack,wherein the stacks are coupled in parallel, when b) applies, the matrixrows each include M active cells coupled to be driven in parallel,wherein at least two matrix rows are coupled in series, and when c)applies, the matrix columns each include N active cells coupled inseries and driven as a stack. The stacks are coupled in parallel and thematrix rows each include M active cells coupled to be driven inparallel. At least two matrix rows are coupled in series. A controlterminal of each active cell is coupled to the amplifier input via asignal path that includes the driver input structure, wherein the activecells are all controllable by an electrical signal input to theamplifier input.

The first and any other aspect can include one or more of the followingfeatures. The driver structure includes a plurality of active drivingelements and the signal path that couples the control terminal of eachactive cell to the amplifier input includes the driving elements. Thesignal path that couples the control terminal of at least some of theactive cells to the amplifier input includes others of the active cells.The control terminal of each active cell is coupled to the amplifierinput to receive a substantially equal input power. Outputs of theactive cells are coupled such that output voltages of the active cellsalong a column are added and output currents of the columns are added atthe amplifier output. Outputs of the active cells are coupled such thatoutput currents of the active cells along a row are added and outputvoltages of the rows are added at the amplifier output. The inputsignals to the control terminals of the transistors in the active cellsin the bottommost row of active cells are unbalanced. Input signals tothe control terminals of the transistors in the active cells in theupper rows of active cells are balanced. The power amplifier includes anactive balun coupled to convert unbalanced signals into balanced inputsignals for the active cells in the upper rows. The balanced inputsignals of the active cells in the upper rows have a current and voltageso that output currents and voltages of the active cells in the upperrows match output currents and voltages of the active cells in thebottommost row. A difference between an output current of a first of theactive cells and an output current of a second, immediately subsequentactive cell in a same column is less than 10% of the output current ofthe first of the active cells. A difference between an output current ofa bottommost of the active cells in a column and an output current of anuppermost active cell in the column is less than 10% of the outputcurrent of the bottommost of the active cells. Output power of each ofthe active cells is substantially equal. A output power of the poweramplifier is substantially equal to N×M the output power of each of theactive cells. The at least one driver structure includes bootstrapcoupling circuitry to distribute a drive signal from a main terminal ofone active cell to a control terminal of another active cell. Thebootstrap coupling circuitry includes a voltage divider or a currentdivider to apply a part of an output voltage or current of a firstactive cell to a control terminal of a second active cell. The bootstrapcoupling circuitry distributes the drive signal from the main terminalof the first active cell in a column to the control terminal of thesecond active cell in same column. The at least one driver structureincludes an active differential driver amplifier. The at least onedriver structure includes one or more passive baluns. The poweramplifier c includes a) an input impedance matching network, b) anoutput impedance matching network, or c) both an input impedancematching network and an output impedance matching network. At least someof the active cells include a) an input impedance matching network, b)an output impedance matching network, or c) both an input impedancematching network and an output impedance matching network. For example,all of the active cells can include an input impedance matching networkand/or all of the active cells can include an output impedance matchingnetwork. The power amplifier includes one or more distribution elementsto distribute a signal from the amplifier input to control terminals ofM bottommost transistors with a substantially same delay. The poweramplifier includes one or more distribution elements to distribute drivesignals to control terminals of the active cells in each row, in eachcolumn, or in both each row and each column with substantially equaldelays. The power amplifier includes one or more collection elements tocollect the output signals from the active cells in each row, in eachcolumn, or in both each row and each column with the output signals arein phase. The power amplifier includes distribution elements todistribute drive signals to control terminals of the active cells ineach row, in each column, or in both each row and each column withdifferent delays, and one or more collection elements to collect theoutput signals from the active cells in each row, in each column, or inboth each row and each column with the output signals out of phase,wherein the collection elements include delays to counter the delays ofthe distribution elements so that power provided to the amplifier outputfrom the active cells is in phase. The power amplifier is implemented inan integrated circuit, for example, in a monolithic microwave integratedcircuit, in a hybrid microwave integrated circuit, or in a multi-chipmodule. The active cells each includes a charge-controlled semiconductorquadrupole transistor, for example, wherein the active cells eachincludes a field effect transistor or a bipolar transistor. The activecells each include a III-V semiconductor-based transistor, for example,a AlGaN/GaN-based transistor or GaAs-based transistor. The active cellseach include a silicon-based transistor, for example, a SiGeheterojunction transistor. The plurality of active cells are part of apush-pull stage. The push-pull stage is a complementary or aquasi-complementary push-pull stage that includes a second plurality ofactive cells. The power amplifier includes a coupling between theamplifier output and a main terminal of a first transistor in an activecell in one of the plurality of active cells and a coupling between theamplifier output and a control terminal of the first transistor. Thecouplings together are to bias the first transistor into conduction inanti-phase with a signal on the amplifier input and thereby enforce ananti-phase operation of the second plurality of active cells relative tothe first plurality of active cells. The coupling between the amplifieroutput and the control terminal of the first transistor includes aconduction path between a main terminal of a transistor in a driverelement and the amplifier output and a conduction path between a controlterminal of the transistor in the driver element and the controlterminal of the first transistor. The coupling between the amplifieroutput and the control terminal of the first transistor consists ofpassive components. Each active cell includes a plurality of transistorsthat are paralleled. Each active cell includes a matrix of transistors.The power amplifier includes first interconnections between thetransistors forming the matrix of transistors of each active cell andsecond interconnections between the active cells themselves. The firstinterconnections are integrated in a semiconductor device on a leveldifferent from the second interconnections. The power amplifier includesa bias tee that has a high frequency port coupled to a load on theamplifier output, a combined port coupled to stacks of thetwo-dimensional matrix, and a low frequency port coupled to a DC source.

In a second aspect, a device includes an antenna assembly having aninput impedance and a power amplifier of the first aspect with orwithout any of the features thereof or of the third aspect, wherein Nand M are configured so that an optimum load impedance of the poweramplifier substantially matches the input impedance of the antennaassembly.

The second and any other aspect can include one or more of the followingfeatures. A reflection coefficient between −12 dB or less can beachieved over a bandwidth limited by the antenna assembly.

In a third aspect, a power amplifier includes a two-dimensional matrixof N×M active cells formed by stacking main terminals of multiple activecells in series, where the stacks are coupled in parallel to form thetwo-dimensional matrix. The power amplifier includes a driver structureto coordinate the driving of the active cells so that the effectiveoutput power of the two-dimensional matrix is approximately N×M theoutput power of each of the active cells.

The third and any other aspect can include one or more of the followingfeatures. The power amplifier includes a bias tee that has a highfrequency port coupled to a load driven by the two-dimensional matrix, acombined port coupled to stacks of the two-dimensional matrix, and a lowfrequency port coupled to a DC source. The power amplifier includes asecond two-dimensional matrix of active cells formed by stacking mainterminals of multiple active cells in series, wherein the stacks arecoupled in parallel to form the second two-dimensional matrix. Thetwo-dimensional matrix and the second two-dimensional matrix are coupledto form a complementary or quasi-complementary stage. The poweramplifier includes a second driver structure to coordinate the drivingof the active cells of the second two-dimensional matrix in anti-phasewith the driving of the active cells in the two-dimensional matrix. Thepower amplifier includes a control loop including an error amplifier tooutput an error signal representative of a difference between a desiredDC output voltage and an actual output voltage. The second driverstructure is coupled to regulate the actual DC output voltage inresponse to the error signal. The two-dimensional matrix and the secondtwo-dimensional matrix are coupled to form the complementary stage. Thepower amplifier includes a second driver structure to coordinate thedriving of the active cells of the second two-dimensional matrix inphase with the driving of the active cells in the two-dimensionalmatrix. The driver structure includes bootstrap coupling circuitry todistribute a drive signal from a main terminal of one active cell to acontrol terminal of another active cell in the same stack. The driverstructure includes a plurality of unbalanced-to-balanced passive balunmatrix drivers. The driver structure includes a row driver to distributea drive signal to control terminals of a plurality of active cells in aplurality of stacks. The row driver includes a plurality of distributionlines to couple portions of a drive signal to the control terminals of aplurality of active cells with appropriate delays to coordinate currentconduction by the active cells. Each of the active cells includes aplurality of transistors coupled in parallel. Each of the active cellsincludes a two-dimensional matrix of transistors. The power amplifierincludes first interconnections between the transistors forming thetwo-dimensional matrix of each active cell and second interconnectionsbetween the active cells themselves. The first interconnections areintegrated in a semiconductor device on a level different from thesecond interconnections. N need not be equal to M. At least some of theactive cells include an input impedance matching network. At least someof the active cells include an output impedance matching network.

In a fourth aspect, a device includes an antenna assembly having aninput impedance and a power amplifier of the third aspect with orwithout any of the features thereof or of the first aspect, wherein Nand M are configured so that an optimum load impedance of the poweramplifier substantially matches the input impedance of the antennaassembly.

The fourth and any other aspect can include one or more of the followingfeatures. A reflection coefficient of −12 dB or less is achieved over abandwidth limited by the antenna assembly.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic representation of a matrix power amplifier.

FIG. 2 is a schematic representation of a matrix power amplifier.

FIG. 3 is a schematic representation of a column-matched matrix poweramplifier.

FIG. 4 is a schematic representation of a column-matched matrix poweramplifier.

FIG. 5 is a schematic representation of a column-matched matrix poweramplifier.

FIG. 6 is a schematic representation of a column-matched matrix poweramplifier.

FIG. 7 shows schematic representation of three implementations of balun.

FIG. 8 is a schematic representation of a column-matched matrix poweramplifier.

FIG. 9 is a schematic representation of a balanced active matrix driverfor a row-matched matrix power amplifier.

FIG. 10 is a schematic representation of an impedance-matchingdifferential amplifier.

FIG. 11 is a schematic representation of a balanced active matrix driverfor a row-matched matrix power amplifier.

FIG. 12 is a schematic representation of a balanced active matrix driverfor a row-matched matrix power amplifier.

FIG. 13 is a schematic representation of a row-matched matrix poweramplifier.

FIG. 14 is a schematic representation of a distribution line and animpedance matching element that can be coupled to distribute a signalfrom signal source to a row of transistors.

FIGS. 15 and 16 are schematic representations of passivedividers/combiners that can be used to implement all or a portion of adistribution rail and a common collection rail.

FIG. 17 is a schematic representation of a distribution line andimpedance matching element that can be coupled to distribute a signalfrom signal source to a row of transistors.

FIG. 18 is a schematic representation of a distribution line andimpedance matching element that can be coupled to distribute a signalfrom signal source to a row of transistors.

FIG. 19 is a schematic representation of a distribution line andimpedance matching element that can be coupled to distribute a signalfrom signal source to a row transistors.

FIG. 20 is a schematic representation of a distribution line andimpedance matching element that can be coupled to distribute signalsfrom pair of signal sources to a row of transistors.

FIG. 21 is a schematic representation of an unbalanced collection railthat is coupled to collect the signals passing through M columns of amatrix power amplifier and direct them to a load.

FIGS. 22 and 23 are schematic representations of a pair of rows within amatrix power amplifier.

FIG. 24 is a schematic representation of a matrix power amplifier.

FIG. 25 is a schematic representation of a matrix power amplifier.

FIG. 26 is a schematic representation of a matrix power amplifier.

FIG. 27 is a schematic representation of a matrix power amplifier.

FIG. 28 is a schematic representation of a matrix power amplifier.

FIG. 29 is a schematic representation of a matrix power amplifier.

FIG. 30a is a schematic representation of a matrix power amplifier.

FIG. 30b is a schematic representation of an impedance-matchingdifferential amplifier.

FIG. 31 is a schematic representation of a matrix power amplifier.

FIG. 32 is a schematic representation of a two-dimensional matrix poweramplifier.

FIG. 33 is a schematic representation of a two-dimensional matrix poweramplifier.

FIG. 34 is a schematic representation of a matrix power amplifier.

FIG. 35 is a schematic representation of a matrix power amplifier.

FIG. 36 is a schematic representation of a push-pull stage 3600 thatincludes a pair of matrix amplifiers.

FIG. 37 is a schematic representation of a push-pull stage that includesa pair of matrix amplifiers.

FIG. 38 is a schematic representation of a two-dimensional matrix poweramplifier that includes a pair of push-pull stages coupled in an“H-type” configuration.

FIG. 39 is a schematic representation of a push-pull stage 3900 thatincludes a pair of matrix amplifiers.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

FIG. 1 is a schematic representation of a matrix power amplifier 100,e.g., for amplifying signals at microwave or millimeter-wavefrequencies. Matrix power amplifier 100 includes a collection of activecells formed by individual transistors 105. Transistors 105 are coupledin multiple stacks 110. Stacks 110 are themselves coupled in parallelbetween an unbalanced distribution rail 115 and an unbalanced collectionrail 120. Distribution rail 115 is coupled to distribute a signal from asignal source 50 to the bottommost transistors 105 in each of stacks110. Collection rail 120 is coupled to collect the signals passingthrough stacks and direct them to a load 70. A matrix driver 125 can bea passive element that distributes drive signals that are generated bysignal source 50 or an active cell that generates drive signals based onthe output of signal source 50. In either case, the drive signals aredistributed to the control terminals of the individual transistors 105via a plurality of balanced row matching structures. In response to thedrive signal, transistors 105 switch from being more conductive to beingless conductive and back again to alternately form multiple higher- andlower-conductivity paths between rails 115, 120 and between signalsource 50 and load 70. Since stacks 110 are coupled in parallel, matrixpower amplifier 100 has an optimum load impedance that can be tailoredto match the impedance of load 70 and hence transfer a relatively largeportion of the maximum possible power thereto.

Matrix power amplifier 100 is a “row-matched” power amplifier in that aplurality of row drivers that are coupled to distribute the drive signalin a row-wise fashion to transistors 105 in different stacks 110. In theillustrated implementation, the transistors 105 of matrix poweramplifier 100 can be considered to be found in four different “rows” 137of the matrix. Although the transistors 105 in each row 137 are found indifferent stacks 110, the transistors 105 in each row 137 are coupled toa respective row matching structure that, in the illustratedimplementation, includes a distribution line 130 and an impedancematching element 135. In the illustrated implementation, impedancematching element 135 is shown as an active driver amplifier. However,impedance matching element 135 can also be formed by a passive impedancematching network. Some portion of each drive signal is coupled to thecontrol terminals on the transistors 105 in each row 137 by thedistribution line 130 and impedance matching element 135. Distributionline 130 and impedance matching element 135 couple the portions of thedrive signals to the control terminals with appropriate delays tocoordinate current conduction by transistors 105 in each row 137, thusamplifying the drive signals. The drive signal coupled into the controlterminal of each transistor 105 is referenced to the potential of thesource/emitter main terminal. The drive signals are “ground-free” in thesense that any control current entering the control terminal of a giventransistor 105 also leaves the transistor 105 by the source/emitter mainterminal but does not contribute to the drain/collector current of the“preceding” transistor 105 in the same stack 110. For the sake ofclarity, in the illustrated schematic representation, the transistor 105that is directly below any given transistor 105 in the same stack 110 isthe “preceding” transistor 105. It is to be understood that theorientation and disposition of components in the illustrated schematicrepresentation is arbitrary and a “preceding” transistor will remain“preceding” notwithstanding a different physical disposition in areal-world device (e.g., above, to the left, or behind a “subsequent”transistor). Instead, “preceding” and “subsequent” transistors can beidentified by their relative disposition in a conductive path betweensignal source 50 and load 70. In any case, instead of contributing tothe drain/collector current of the preceding transistor 105, the currentthat leaves the transistor 105 by the source/emitter main terminalreturns to impedance matching element 135 by way of distribution line130 that is located directly below that transistor 105.

In the illustrated implementation, signal source 50 is an RF source thatoutputs a signal that achieves the desired current flow between the mainterminals of the active cells in matrix power amplifier 100. Forexample, signal source 50 can output a signal that represents a desiredcommunications transmission. In some implementations, signal source 50can output a signal having a carrier or center frequency of betweennearly DC (generally, a few 100 MHz so that different transistors arecapacitive decoupled) and approx. 1/3 f_(T), where f_(T) is the unitygain transition frequency of transistors 105. For example, in some III-Vfield effect transistors, f_(T) can be 30 GHz or so. Some portion of thesignal output by input signal source 50 is coupled into rail 115 by animpedance matching element 135. In the illustrated implementation,impedance matching element 135 is shown as an active driver amplifier.Thus, in the illustrated implementation, signal source 50 does notdirectly output a drive signal that drives the control terminals oftransistors 105. Rather, signal source 50 outputs a signal that isamplified by impedance matching element 135 to generate such a drivesignal. In other implementations, impedance matching element 135 can beformed by a passive impedance matching network. In such implementations,signal source 50 can directly output a drive signal that drives thecontrol terminals of transistors 105.

Distribution rail 115 is coupled to distribute portions of thecommunications signal and a DC signal to both the control terminals andthe source/emitter main terminals of the transistors 105 in a first row138. In some implementations, impedance matching element 135 can act asa balun and distribution rail 115 can be implemented as a two wiretransmission line that is symmetric to earth. Distribution rail 115terminates in an RF loading and gate biasing network 140. In theillustrated implementation, RF loading and gate biasing network 140includes a DC source 145 that outputs a DC signal which controls thecurrent flow through stacks 110 via the control terminals of transistors105 in the first row 138. In particular, once current begins to flowthrough transistors 105 in the first row 138, current flow in subsequentrow 137 follows. In the illustrated implementation, the potential outputfrom DC source 145 is negative with respect to ground and pulls down thepotential on collection rail 120 when stacks 110 are conductive. Thepotential output by DC source 145 is isolated from the grounded wire ofthe two wire transmission line of distribution rail 115 by a capacitance150 and coupled to the other wire by an impedance 155. In theillustrated implementation, impedance 155 is a real impedance thatprovides a portion of the load that is matched by impedance matchingelement 135.

Collection rail 120 collects the power output from each stacks 110 anddirects it toward load 70. Collection rail 120 can also be implementedas a two wire transmission line that is symmetric to earth. In eithercase on of the wires of collection rail 120 is coupled to the combinedport of a high voltage bias tee 170. Load 70 is coupled to the highfrequency port of the bias tee 170, and DC source 160 is coupled to thelow frequency port. The ungrounded wires are thus biased by DC source160 with a DC potential suitable for powering matrix power amplifier100. In the illustrated implementation in which impedance matchingelements 135 are implemented as active driver amplifiers, the DCpotential output by DC source 160 is conducted by one or more powerlines 168 to those active driver amplifiers.

In the illustrated implementation, power amplifier 100 includes acollection of individual transistors 105. Transistors 105 can be any ofa number of different types of semiconductor devices, e.g., field effecttransistors (FETs) or bipolar junction transistors (BJTs), with orwithout any individual matching or prematching. In some implementations,the active cells of the matrix of power amplifier 100 are not individualtransistors but rather multiple transistors, e.g., assembled intoamplifier modules.

FIG. 2 is a schematic representation of a matrix power amplifier 200.Matrix power amplifier 200 also includes individual transistors 105 thatare coupled in multiple stacks 110. Stacks 110 are themselves coupled inparallel between unbalanced distribution rail 115 and unbalancedcollection rail 120. In contrast with power amplifier 100 (FIG. 1),distribution rail 115 is necessarily unbalanced since matrix poweramplifier 200 does not include an impedance matching element 135 thatcan potentially act as a balun between signal source 50 and distributionrail 115.

Matrix power amplifier 200 is a “column-matched” power amplifier in thatmatrix power amplifier 200 includes a plurality of column drivers 205that are coupled to distribute the drive signal in a column-wise fashionto transistors 105 respective of stacks 110. In the illustratedimplementation, the transistors 105 of matrix power amplifier 200 can beconsidered to be found in four different “columns” 237 of the matrix.The transistors 105 in each column 237 are found in the same stack 110and coupled to a single column driver 205. Column drivers 205 can beimplemented in a variety of different ways, including (passive)bootstrapping column drivers and (active) column drivers that include,e.g., differential amplifiers, including those described below. Columndrivers 205 can be active or passive elements.

Each column driver 205 includes a control terminal coupling 210 and amain terminal coupling 215. Control terminal couplings 210 couple columndriver 205 to the control terminals of respective transistors 105. Mainterminal couplings 215 couple column driver 205 to the source/emittermain terminals of respective transistors 105. The drive signal coupledinto the control terminal of each transistor 105 is referenced to thepotential of the source/emitter main terminal. Aside from first row 138(discussed below), terminal couplings 210, 215 form a balanced couplingfor driving transistors 105. In effect, the drive signals areground-free and any control current entering the control terminal of agiven transistor 105 also leaves the transistor 105 by thesource/emitter main terminal but does not contribute to thedrain/collector current of the preceding transistor 105 in the samestack 110.

In first row 138 of matrix power amplifier 200, the source/emitter mainterminal of transistors 105 are all coupled to ground. As a consequence,main terminal couplings 215 to the source/emitter main terminals oftransistors 105 in first row 138 are also coupled to ground and thusform an unbalanced coupling. As with matrix power amplifier 100 (FIG.1), DC source 145 controls the current that is to flow through stacks110 via the control terminals of transistors 105 in the first row 138.

FIG. 3 is a schematic representation of a column-matched matrix poweramplifier 300. For the sake of convenience, only a single stack 110 (andhence a single column) of matrix power amplifier 300 is illustrated.However, it is to be understood that matrix power amplifier 300 caninclude a number of rows and columns that is tailored to operationalneeds, including output impedance and amplification.

Matrix power amplifier 300 includes an unbalanced passive matrix driver305 that distributes signals generated by signal source 50 to acollection of balanced distribution lines 310. Each distribution line310 couples a respective portion of the drive signal to transistors 105in different stacks 110. Once again, only a single stack 110 isillustrated in the schematic representation of matrix power amplifier300 although an operational matrix power amplifier 300 will includemultiple stacks 110.

Unbalanced passive matrix driver 305 is coupled to each balanceddistribution lines 310 by a balun transformer 315. Balun transformers315 not only convert the unbalanced signal on passive matrix driver 305to a balanced signal on distribution lines 310, but balun transformers315 also act as impedance matching elements to couple the drive signalto transistors 105 in different stacks 110.

Each balanced distribution line 310 includes a conductive path 320 thatcouples a first terminal of the balun transformer 315 winding to thesource/emitter main terminals of transistors 105, a conductive path 325couples the other, second terminal of the balun transformer 315 windingto the control terminals of transistors 105, and a conductive path 330between either a center tap 345 of the respective balun transformer 315or the second terminal of the respective balun transformer 315 to a DCsource 335 relative to ground. Each DC source 335 biases a controlterminal of a respective transistor 105. Each source/emitter conductivepath 320 includes a capacitance 340 that isolates the remainder ofdistribution line 310 from the DC potential on the respectivesource/emitter of terminals of transistors 105. DC source conductivepaths 330 each includes an inductance 350 that isolates the RF signalfrom DC sources 335.

FIG. 4 is a schematic representation of a column-matched matrix poweramplifier 400. For the sake of convenience, only a single stack 110 (andhence a single column) of matrix power amplifier 400 is illustrated.However, it is to be understood that matrix power amplifier 400 caninclude a number of rows and columns that is tailored to operationalneeds, including output impedance and amplification.

Matrix power amplifier 400 uses parallel bootstrapping driver circuits405 to distribute signals generated by signal source 50 to transistors105 in stack 110. The parallel bootstrapping driver circuits 405transfer a portion of the output voltage, e.g., drain/collector voltageof each respective transistor 105 (e.g., a kth stage transistor 105) todrive the control terminal of a respective “subsequent” transistor 105(e.g., a (k+1)^(th) stage transistor 105) in the stack 110.

Each parallel bootstrapping driver circuit 405 includes impedanceelements 415 and capacitances 420. Impedance elements 415 are arbitrarypassive complex impedances and can include one or more inductors,capacitors, and/or passive resistive elements. Impedance elements 415 ofdriver circuit 405 form an AC voltage divider circuit that transfers aportion of the output voltage of each respective preceding transistor(e.g., kth stage) to the control terminal of a respective subsequenttransistor 105 ((k+1)th stage) in the stack 110. For example, theimpedance elements 415 of a kth stage driver circuit 405 form a voltagedivider between the voltage at an upper main terminal 436 (e.g.,drain/collector) of a kth stage transistor 105 and the voltage at alower main terminal 437 (e.g., source/emitter) of the kth stagetransistor 105. The output of the kth stage driver circuit 405 (e.g., aterminal between the impedance elements 415) is provided to the inputterminal (e.g., gate) of the (k+1)th stage transistor 105.

“Upper” main terminals of transistors 105 are terminals that aredisposed toward the output end of a stack 110 (i.e., nearest collectionrail 120) in the conductive path between signal source 50 and load 70.In the illustrated schematic representations, all of the upper mainterminals are drain/collector terminals, although this is notnecessarily the case. “Lower” main terminals of transistors 105 areterminals that are disposed toward the input end of a stack 110 (i.e.,nearest distribution rail 115). In the illustrated schematicrepresentations, all of the lower main terminals are source/emitterterminals, although this is not necessarily the case.

Capacitances 420 isolate the drive signal for each subsequent transistor105 from the DC potentials on the respective source/emitter anddrain/collector terminals of the preceding transistor 105. The totaloutput power of the stack 110 decreases as the frequency of the signalsgenerated by signal source 50 increases because a part of the powergenerated by each transistor 105 in the stack is used to drive arespective subsequent transistor 105.

Distribution rail 115 and an impedance matching element 410 conduct aportion of the signal generated by signal source 50 to bottom row 406transistors 105 in different stacks 110, but the upper row 407 oftransistors 105 are driven with input signals from the voltage dividersor driver circuits 405. Similarly, output impedance matching elements455 couple the output signal of each stack 110 to collection rail 120.Once again, only a single stack 110 is illustrated in the schematicrepresentation of matrix power amplifier 400, although an operationalmatrix power amplifier 400 will include multiple stacks 110. The controlterminal of each kth stage transistor 105 (except for the first stage)is biased by a DC voltage divider circuit 430. The DC voltage dividercircuits 430 each include resistances 435 that divide the voltagebetween an upper main terminal 436 (e.g., drain/collector) of that kthstage transistor 105 and the lower main terminal 437 of each “preceding”(e.g., (k-1)th stage) transistor 105. The first (lowest) stagetransistor 105 is biased by DC source 145.

Distribution lines 440 couple both the bootstrapped drive signal andstack current between transistors 105 in the stack. The distributionlines 440 are three-line transmission lines including two signal lines445 and one ground line 450. In each distribution line 440, one signalline 445 carries the bootstrapped drive signal and the other signal line445 carries the stack current between the transistors 105.

FIG. 5 is a schematic representation of a column-matched matrix poweramplifier 500. For the sake of convenience, only a single stack 110 (andhence a single column) of matrix power amplifier 500 is illustrated.However, it is to be understood that matrix power amplifier 500 caninclude a number of rows and columns and be tailored to operationalneeds, including output impedance and amplification. Matrix poweramplifier 500 is similar to matrix power amplifier 400 (FIG. 4), exceptthat the control terminal of each transistor 105 is biased by a DCvoltage source 505 instead of a DC voltage divider circuit 430.Furthermore, each DC source is isolated from RF signals by an inductance510.

As with matrix amplifier 400, the distribution lines 440 of matrixamplifier 500 couple both the bootstrapped drive signal and stackcurrent between transistors 105 in the stack. The distribution lines 440are three-line transmission lines including two signal lines 445 and oneground line 450. In each distribution line 440, one signal line 445carries the bootstrapped drive signal and the other signal line 445carries the stack current between the transistors 105.

The bootstrapping driver circuits 405 of matrix amplifiers 400 and 500are considered to be parallel boot-strapped because the bootstrappeddrive signal is obtained through a voltage divider which is parallelconnected to the transistor stack. In addition, the bootstrapped drivesignal and stack current are each coupled between transistors 105 in thestack through different signal lines 445 in the distribution lines 440.

FIG. 6 is a schematic representation of a column-matched matrix poweramplifier 600. For the sake of convenience, only a single stack 110 (andhence a single column) of matrix power amplifier 600 is illustrated.However, it is to be understood that matrix power amplifier 600 caninclude a number of rows and columns that is tailored to operationalneeds, including output impedance and amplification.

Matrix power amplifier 600 uses series bootstrapping to distributesignals generated by signal source 50 to transistors 105 in a stack 110.Baluns 605 transfer a portion of the output current (e.g., thedrain/collector current) from each transistor 105 in the lower rows 606,607 of the matrix power amplifier 600 to drive the control terminal ofrespective subsequent transistors 105 in the stack 110. Baluns 605 arethree-terminal devices that both couple a portion of the output currentfrom a transistor in one of the lower rows 606, 607 as a controlterminal drive signal for a respective subsequent transistor 105 in thenext higher row and convert the unbalanced output current to a balanceddrive signal.

FIG. 7 shows schematic representation of three implementations of balun605. The first implementation is a transformer 605 a. The transformer605 a includes a primary coil 705 and a secondary coil 710 and a commonterminal 715 coupled to both the primary coil 705 and the secondary coil710. In some implementations, the nominal value of the transformationratio of transformers 605 a is selected to match the current gain of thetransistors 105. When the transformer 605 a is used as the balun 605 inthe matrix power amplifier 600, a terminal of the primary coil 705 iscoupled to an upper main terminal 636 (e.g., drain/collector) of atransistor 105, the common terminal 715 is coupled to a lower mainterminal 637 (e.g., source/emitter) of a respective subsequenttransistor 105, and a terminal of the secondary coil 710 is coupled to acontrol terminal of the respective subsequent transistor 105. Thus, theoutput signal secondary coil 710 supplies the input drive signal to thecontrol terminal of the respective subsequent transistor 105.

The second implementation of balun 605 is a T-circuit 605 b includingthree admittance elements 720 configured T (or wye) network. The thirdimplementation of balun 605 is a pi-circuit 605 c including threeimpedance elements 730 configured in a pi (or delta) network. Differentimplementations of balun 605 can be used in different real-worldimplementations of matrix power amplifiers. For example, the admittanceelements 720 of T-circuit 605 b may be advantageous in some microwaveintegrated circuit devices, whereas the impedance elements 730 of thepi-circuit 605 c may be advantageous in others, depending on factorssuch as processing technology and the design of other components in thematrix power amplifier.

Referring again to FIG. 6, capacitances 620 are included in theconductive path between the baluns 605 and control terminals of thetransistors 105. Capacitances 620 isolate the drive signal for eachtransistor 105 from DC potential on the respective source/emitter anddrain/collector terminals of transistors 105. Furthermore, the totaloutput power of the stack 110 decreases as the frequency of the signalsgenerated by signal source 50 increases because a part of the powergenerated by each transistor 105 in the stack is used to drive arespective subsequent transistor 105.

Distribution rail 115 carries a respective portion of the signalsgenerated by signal source 50 to bottom row 606 transistors 105 indifferent stacks 110. The impedance matching elements 610 couple thesource signal on distribution rail 115 to the bottom row 606 transistors105 in different stacks 110. Similarly, output impedance matchingelements 655 couple the output signal of each stack 110 to collectionrail 120. Once again, only a single stack 110 is illustrated in theschematic representation of matrix power amplifier 600 although anoperational matrix power amplifier 600 will include multiple stacks 110.

The control terminal of each transistor 105 is biased by a DC voltagedivider circuit 630. DC voltage divider circuits 630 each includeresistances 635 that divide the voltage between an upper main terminal(e.g., drain/collector) 636 of a transistor 105 and a lower mainterminal (e.g., source/emitter) 637 of a preceding transistor 105. Eachof the DC voltage divider circuits 630 provides a floating bias to thecontrol input of a respective transistor 105. The exception is the DCvoltage divider circuit 630 connected to the lower main terminal of thetransistor 105 in the bottom row 606, which is grounded.

Distribution lines 640 couple transistors 105 in the stack. Thedistribution lines 640 are unbalanced three-line transmission linesincluding two signal lines 645 and one ground line 650. Generally, theDC voltage divider circuits 630 are coupled to one of the signal lines645 and respective transistor 105 upper and lower main terminals arecoupled to the other signal line 645. The distribution line 660 couplingthe transistor 105 in the bottom row 606 to the first subsequent row 607is an unbalanced two-line transmission line. Distribution line 660includes one signal line 645 and one ground line 650. The signal line645 in distribution line 660 is coupled to the upper main terminal oftransistor 105 in the bottom row 606 and the lower main terminal oftransistor 105 in the subsequent (second) row. The DC voltage dividercircuit 630 that is connected to the lower output of the transistor inthe bottom row 606 is coupled to the ground line 650 in distributionline 660.

FIG. 8 is a schematic representation of a column-matched matrix poweramplifier 800. For the sake of convenience, only a single stack 110 (andhence a single column) of matrix power amplifier 800 is illustrated.However, it is to be understood that matrix power amplifier 800 caninclude a number of rows and columns that is tailored to operationalneeds, including output impedance and amplification. Matrix poweramplifier 800 is similar to matrix power amplifier 600 described abovein reference to FIGS. 6 and 7, except that the control terminal of eachtransistor 105 is biased by a DC voltage source 805 instead of a DCvoltage divider circuit 630. Furthermore, each DC source is isolatedfrom RF signals by an inductance 810. In addition, the three-linedistribution lines 660 of matrix power amplifier 600 can be replaced bybalanced two-line distribution lines 815 which include two balancedsignal lines 645 and no ground line.

FIG. 9 is a schematic representation of a balanced active matrix driver905 for a row-matched matrix power amplifier 900. For the sake ofconvenience, only a single stack 110 (and hence a single column) ofmatrix power amplifier 900 is illustrated. However, it is to beunderstood that matrix power amplifier 900 can include a number of rowsand columns that is tailored to operational needs, including outputimpedance and amplification.

The balanced active matrix driver 905 distributes signals generated bysignal source 50 to a collection of balanced distribution lines 910.Each distribution line 910 couples a respective portion of the drivesignal to transistors 105 in different stacks 110. Once again, only asingle stack 110 is illustrated in the schematic representation ofmatrix power amplifier 900 although an operational matrix poweramplifier 900 will include multiple stacks 110.

The balanced active matrix driver 905 includes a set of stackedimpedance-matching differential amplifiers 915. The balanced activematrix driver 905 includes one less impedance-matching differentialamplifiers 915 than transistors 105 in each stack 110. For instance, inthe example shown, the active matrix driver 905 includes threeimpedance-matching differential amplifiers 915 to drive a stack 110 offour transistors 105. The first differential amplifier 915 and thetransistor 105 in the bottom row (row 1) of the stack are simultaneouslydriven by the signal source 50. Each k-th differential amplifier 915 inthe active matrix driver 905 then drives the (k+1)-th transistor 105 instack 110.

In more detail, FIG. 10 is a schematic representation of animpedance-matching differential amplifier 915 that can be used inbalanced active matrix drivers. Differential amplifier 915 includes aninverting input terminal 1080, a non-inverting input terminal 1082, ahigh output terminal 1084, and a low output terminal 1086. Differentialamplifier 915 outputs a signal on output terminals 1084, 1086 thatrepresents the difference between the signal on input terminals 1080,1082.

Referring again to FIG. 9, the differential amplifiers 915 are stackedwith the output terminals 1084, 1086 of each differential amplifier 915(k-th differential amplifier 915) coupled to the input terminals 1080,1082 of the next subsequent differential amplifier 915 ((k+1)-thdifferential amplifier 915) in the active matrix driver 905. In someimplementations, an impedance matching network (not shown) can becoupled between each of the differential amplifiers 915. In addition,the output terminals 1084, 1086 of each differential amplifier 915 arecoupled to a balanced distribution line 910 that provides a drive signalto a respective transistor 105 in rows 2 through N of the stack 110.

Each balanced distribution line 910 includes a conductive path 920 thatcouples a first output terminal 1084, 1086 of the differential amplifier915 to the source/emitter main terminal of a transistor 105 and aconductive path 325 that couples the other output terminal 1084, 1086 ofthe differential amplifier 915 to the control terminals of thetransistor 105. Each source/emitter conductive path 920 includes acapacitance 940 that isolates the remainder of distribution line 910from the DC potential on the respective source/emitter of terminals oftransistors 105. More specifically, the non-inverting output terminal1086 of the second through N-th differential amplifier 910 is coupled tothe control terminal conductive path 925 and the inverting outputterminal 1084 of the second through N-th differential amplifier 910 iscoupled to the source/emitter conductive path 920. However, theconnection of the output terminals 1084, 1086 of the first differentialamplifier 915 with the distribution line 910 are swapped. That is, theinverting output terminal 1084 of the first differential amplifier 910is coupled to the control terminal conductive path 925 and thenon-inverting output terminal 1086 of the first differential amplifier910 is coupled to the source/emitter conductive path 920.

Furthermore, in some implementations, the distribution lines 910 caninclude an impedance matching network (not shown) to match the impedanceof the differential amplifier 915 output terminals 1084, 1086 to theinput impedance of the transistors 105.

Differential amplifiers 915 are supplied by two separate DC paths; anODD and an EVEN path. Odd numbered differential amplifiers 915 (1through N) are supplied by the ODD path and even numbered differentialamplifiers 915 (1 through N) are supplied by the EVEN path. Each DC pathis supplied by a source follower circuit 950, 955 and coupled to thehigh supply 1090 terminal of the highest order (N or N−1) differentialamplifier 915 in the respective ODD or EVEN path. More specifically, thehigh supply terminal 1090 of the N-th differential amplifier 915 iscoupled to source follower circuit 950 (the ODD DC path). Whereas, thehigh supply terminal 1090 of the (N−1)-th differential amplifier 915 iscoupled to source follower circuit 955 (the EVEN DC path).

Conductive path 956 couples the low supply terminal of the N-thdifferential amplifier 915 to the high supply terminal of the next lowerorder ODD differential amplifier 915 in the active matrix driver 905,specifically, the first differential amplifier 915, in the exampleshown. The low supply terminal of the first differential amplifier 915is coupled to a negative DC source.

The low supply terminal of the (N−1)-th (here the second) differentialamplifier 915 is coupled to ground in the example shown. However, in alarger active matrix driver 905 stack the low supply terminal of the(N−1)-th differential amplifier 915 can be coupled to the high supplyterminal next lower order even differential amplifier 915 by aconductive path.

Source follower 950 includes a pair of matched transistors 952 that eachare coupled between a high drain-side potential and a low source-sidepotential. The high drain-side potential (terminal 960) is coupled tothe RF collection rail 120. The low source-side potential is coupledbetween impedances 965 a and 965 b of a voltage divider circuit. Thevoltage divider circuit is created by impedances 965 a, 965 b, and 965 calso coupled to the terminal 960 and the RF collection rail 120. Theimpedances 965 a, 965 b, and 965 c divide the RF output voltage from thecollection rail 120 to bias the control terminals of transistors 952,which are coupled to the voltage divider circuit between impedances 965a and 965 b. The source terminals of the transistors 952 are coupled tothe voltage divider circuit between impedances 965 a and 965 b through acapacitance 954 a and to the low supply terminal of the N-thdifferential amplifier 915. The capacitance 954 a isolates the lowsupply terminal of the N-th differential amplifier 915 from the DCpotential on the RF collection rail 120.

Source follower 955 includes a transistor 953 that is coupled between ahigh drain-side potential and a low source-side potential. The highdrain-side potential is coupled to voltage divider circuit betweenimpedances 965 a and 965 b and to the source terminals of transistors952. The low source-side potential is coupled between impedances 965 band 965 c of the voltage divider circuit. The source terminal oftransistor 953 is coupled to the voltage divider circuit betweenimpedances 965 b and 965 c through a capacitance 954 b and to the lowsupply terminal of the (N−1)-th differential amplifier 915. Thecapacitance 954 b isolates the low supply terminal of the (N−1)-thdifferential amplifier 915 from the DC potential on the RF collectionrail 120.

The source followers 950, 955 are supplied by the RF output signal ofthe matrix power amplifier 900 through the RF collection rail 120. Thus,all of the high and low supply terminals of the differential amplifiers915 are under floating AC potential, and can accommodate the full RFvoltage output swing of the corresponding transistors 105 in the stack110.

FIG. 11 is a schematic representation of a balanced active matrix driver905 for a row-matched matrix power amplifier 1100. For the sake ofconvenience, only a single transistor stack 110 of FIG. 1 (and hence asingle transistor 105 column) of matrix power amplifier 1100 isillustrated. However, it is to be understood that matrix power amplifier1100 can include a number of rows and columns that is tailored tooperational needs, including output impedance and amplification.

The balanced active matrix driver 1105 distributes signals generated bysignal source 50 to a collection of balanced distribution lines 1110.Each distribution line 1110 couples a respective portion of the drivesignal to transistors 105 in different stacks 110. Once again, only asingle transistor stack 110 is illustrated in the schematicrepresentation of matrix power amplifier 1100 although an operationalmatrix power amplifier 1100 will include multiple stacks 110.

The balanced active matrix driver 1105 includes a set of stackeddifferential amplifiers 1115. The first differential amplifier 1115 andthe transistor 105 in the bottom row (the first row) of the stack aresimultaneously driven by the signal source 50. Each k-th differentialamplifier 1115 in the active matrix driver 1105 then drives the (k+1)-thtransistor 105 in stack 110.

Differential amplifiers 1115 each include a pair of matched transistors1194 that each are coupled between a high drain-side potential and a lowsource-side potential. Only the first differential amplifier 1115includes a current source 1188. Except for the N-th differentialamplifier 1115, the high drain-side potential for each k-th differentialamplifier 1115 is supplied by the low-source side potential of the(k+1)-th differential amplifier 1115. The high drain-side potential forthe N-th differential amplifier 1115 is supplied by the RF collectionrail 120. Similarly, except for the first differential amplifier 1115,the low source-side potential for each k-th differential amplifier 1115is supplied by the high-source side potential of the (k−1)-thdifferential amplifier 1115. The low source-side potential for the firstdifferential amplifier 1115 is supplied by the DC supply 1150. Thus, thedifferential amplifiers 1115 are stacked such that the DC currentthrough the first differential amplifier 1115 is reused by eachdifferential amplifier in the active matrix driver 1105.

The differential amplifiers 1115 in the active matrix driver 1105 arecoupled together through balanced distribution lines 1135. In someimplementations, an impedance matching network (not shown) also can becoupled between each of the differential amplifiers 1115. In addition,the output terminals 1184 of each differential amplifier 1115 (exceptthose of the N-th differential amplifier 1115) are coupled to a balanceddistribution line 1110 that provides a drive signal to a respectivetransistor 105 in rows two through N of the stack 110.

Each balanced distribution line 1110 includes a conductive path 1120that couples a first output terminal 1184 of the differential amplifier1115 to the source/emitter main terminal of a transistor 105 and aconductive path 1125 that couples the other output terminal 1184 of thedifferential amplifier 1115 to the control terminal of the transistor105. Each source/emitter conductive path 1120 includes a capacitance1140 that isolates the remainder of distribution line 1110 from the DCpotential on the respective source/emitter of terminals of transistors105. Furthermore, in some implementations, the distribution lines 1110can include an impedance matching network (not shown) to match theimpedance of the differential amplifier 1115 output terminals 1084, 1086to the input impedance of the transistors 105.

In addition, the control terminals of the transistors 1194 (inputsterminals 1182 of the differential amplifiers 1115) are coupled outputterminals 1184 of each preceding, (k−1)-th, differential amplifier 1115.The potential drop across each set of impedances 1196 is used to drivethe input (control terminals of transistors 1194) of each differentialamplifier 1115, except for the first differential amplifier 1115. Thecontrol terminal of the first of the transistors 1194 in the firstdifferential amplifier 1115 is driven by the RF source 50 and thecontrol terminal of the second of the transistors 1194 is biased with aDC potential from DC source 145. The control terminal of the first ofthe transistors 1194 in the first differential amplifier 1115 is coupledto the RF source 50 through an impedance matching network 1130.

As shown, the sources of transistors 1194 of the first differentialamplifier 1115 are coupled together and share a common path to thecurrent source 1188. The impedance between both output terminals 1184and current source 1188 is thus nearly identical except for therelatively small differences in the impedance of transistors 1194. Thefirst differential amplifier 1115 can thus act as a balun and convertthe unbalanced RF source signal into a balanced output.

Furthermore, the control terminal of one of the transistors 1194 of eachof the differential amplifiers 1115 two through N is biased by a portionof the RF output signal from RF collection rail 120. A voltage dividercircuit 1160 created by the network of impedances 1162 divides thevoltage of the RF output signal.

Current source 1188 provides the DC current for all of the differentialamplifiers 1115 in the active matrix driver 1105. Current source 1188includes a transistor 1189 that supplies the current throughdifferential amplifiers 1115. The control terminal of transistor 1189 isbiased by the DC source 1150 through impedance 1191. In addition, thesource terminal of transistor 1189 is coupled to DC source 1150 throughimpedance 1193.

FIG. 12 is a schematic representation of a balanced active matrix driver1205 for a row-matched matrix power amplifier 1200. For the sake ofconvenience, only a single transistor stack 110 (and hence a singletransistor 105 column) of matrix power amplifier 1200 is illustrated.However, it is to be understood that matrix power amplifier 1200 caninclude a number of rows and columns that is tailored to operationalneeds, including output impedance and amplification. Balanced activematrix driver 1205 is similar to balanced matrix driver 1105 describedabove in reference to FIG. 11, except that the first row transistor 105is not driven directly by the RF signal from RF source 50. Instead,matrix driver 1205 includes an additional differential amplifier 1115.The RF source 50 only drives the first differential amplifier 1115through a set of source follower circuits 1210. As shown, the sourcefollowers 1210 can be combined with a resistance that acts as a DCpotential shifter to shift the zero DC level of the RF source to thenegative gate voltage required by the FET pair in the bottom-mostdifferential amplifier that operates at negative DC voltages below thegate voltage potential of the lowest row of the matrix amplifier.Alternatively, a diode chain can be used as such a DC potential shifter.

FIG. 13 is a schematic representation of a row-matched matrix poweramplifier 1300. In the illustrated implementation, each row distributionline 130 is implemented as a balanced two conductor transmission-linethat terminates in a real impedance 1310 and a capactive impedance 1315.The first conductor of the transmission-line is formed by a series ofconductors 1320 that each couple to respective control terminals oftransistors 105 of a row 137. The second conductor of thetransmission-line is formed by a series of conductors 1325 that coupleto the source/emitter main terminals of transistors 105 in the same row137. Conductors 1320, 1325 are dimensioned to delay the arrival of drivesignals at the control terminals of transistors 105 so that currentconduction by transistors 105 in matrix power amplifier 1300 iscoordinated. In particular, the current signals of the transistors 105in each row 137 are collected in a column-wise manner in the commoncollection rail 120 with delays that match the corresponding delays onthe row distribution lines 130. The values of impedances 1310, 1315 areconfigured to set the impedance of row distribution line 130 so that adrive signal is appropriately coupled thereto from matrix driver 125. Asdiscussed previously, matrix driver 125 can be an active or passivedriver that provides ground-free outputs for each row distribution line130.

In power amplifier 1300, artificial LC or distributed transmission linesare used. This implementation can be used as feeders for the bottominput line and for driving the input of the upper rows. The input of thebottom row and the output of the top row can be the same as the inputand output of the driver lines, respectively, of a Field-effectTransistor (FET) or Bipolar Junction Transistor (BJT) distributedamplifier or a non-uniform distributed power amplifier (NDPA) structure.Symmetric (e.g., ground-free) feeder networks are used for the inputlines of the second and upper rows. The input rails of the upper rowsare driven by a passive or active driver/feeder network that providessymmetric (e.g., ground-free) outputs for the individual rows.

FIG. 14 is a schematic representation of a distribution line 130 and animpedance matching element 135 that can be coupled to distribute asignal from signal source 50 to a row of transistors 105. Theillustrated implementation of distribution line 130 and impedancematching element 135 includes a collection of column-to-columnconductors 1405, stack conductors 1407, and impedance matching elements1410.

Each impedance matching element 1410 is associated with a respectivestack 110 and includes a control terminal output 1415 and a mainterminal output 1420. Control terminal outputs 1415 are to be coupled toa respective control terminal of a transistor 105 in the associatedstack 110. Main terminal outputs 1420 are to be coupled to a respectivemain terminal of the same transistor 105 in the associated stack 110.Each impedance matching element 1410 can nominally match the inputimpedance of the transistors 105 to a reference impedance ZL of thesource. In some implementations, this impedance can be raised, e.g. to2*ZL. This can be done, e.g., using quarter-line transformers,line-capacitors, or discrete LC transformers.

Each stack conductor 1407 is associated with a respective stack 110.Column-to-column conductors 1405 are coupled between the stackconductors 1407 that are associated with adjacent stacks 100. Stackconductors 1407 and column-to-column conductors 1405 are dimensioned todelay the arrival of drive signals at the control terminals of thetransistors 105 in each stack so that current conduction by transistors105 in the matrix power amplifier is coordinated. In the illustratedimplementation, stack conductors 1407 and column-to-column conductors1405 are unbalanced conductors and—together with main terminal outputs1420—are coupled to a reference potential. In the illustratedimplementation, this reference potential is ground.

This combination of column-to-column conductors 1405, stack conductors1407, and impedance matching elements 1410 can be referred to as a“cascaded line and prematch” topology. In particular, conductors 1405,1407 are cascaded to distribute the drive signal to coordinate currentconduction in the difference stacks 110. Impedance matching elements1410 ensure that a sufficiently large portion of the drive signal iscoupled into the transistors 105 in each stack 110. Such a distributionline 130 and an impedance matching element 135 can be particularlyadvantageous in microwave integrated circuit implementations, includingplanar monolithic implementations. In particular, due to the limitedarea available for distribution line 130 and an impedance matchingelement 135, the ability to implement a compact “cascaded line andprematch” topology using semiconductor fabrication techniques can beadvantageous.

In some implementations, a corresponding “cascaded line and prematch”topology can be used to form either or both of distribution rail 115 andcommon collection rail 120. For example, the bottommost transistor 105in each stack 110 can be coupled to a respective impedance matchingelement and the signal passing column-to-column conductors 1405 andstack conductors 1407 suitably delayed to coordinate current conductionthrough the stacks in response to the signal output from source 50. Asanother example, the uppermost transistor 105 in each stack 110 can becoupled to a respective impedance matching element and the currentpassing through these uppermost transistor 105 suitably delayed usingstack conductors and column-to-column conductors for delivery to theload 70.

FIGS. 15 and 16 are schematic representations of passivedividers/combiners 1500, 1600 that can be used to implement all or aportion of distribution rail 115 and common collection rail 120. In theillustrated implementations, dividers/combiners 1500, 1600 each includea respective root terminal 1505, 1605, a trunk portion 1510, 1610, and acollection of branch terminals 1515, 1615.

When dividers/combiners 1500, 1600 are part of distribution rail 115,root terminals 1505, 1605 act as inputs to be coupled to receive asignal from source 50 and branch terminals 1515, 1615 act as outputs todistribute that signal to the drive terminals of the bottommosttransistor 105 in each stack. When dividers/combiners 1500, 1600 arepart of collection rail 120, root terminals 1505, 1605 act as outputs toload 70 and branch terminals 1515, 1615 act as inputs to receive thecurrents conducted through respective of stacks 110. Trunk portions1510, 1610 couple the root terminals and branch terminals and providesymmetric passive M-to-1 or 1-to-M coupling.

In some implementations, dividers/combiners 1500, 1600 are used inconjunction with impedance matching elements. However, this is notnecessarily the case. For example, dividers/combiners 1500, 1600 can beused in matrix power amplifiers that include “bootstrapping” row drivertopologies (e.g., FIGS. 4-8) without impedance matching elements.

FIG. 17 is a schematic representation of a distribution line 130 andimpedance matching element 135 that can be coupled to distribute asignal from signal source 50 to a row of transistors 105. In general,the row of transistors 105 into which distribution line 130 andimpedance matching element 135 distribute a signal will be one of thehigher rows of a matrix rather than a bottom row. However, in someimplementations, distribution line 130 and impedance matching element135 may also be used to distribute a signal to a bottom row of a matrixamplifier. The illustrated implementation of distribution rail 115includes a global input impedance matching element 1705,column-to-column conductors 1710, and local impedance matching elements1715.

Global input impedance matching element 1705 is a device that matchesthe input impedance 1725 of a chain of transmission lines 1710 andimpedance matching elements 1715 to the input impedance 1720 of matchingelement 1705 seen by source 50. In some implementations, global inputimpedance matching element 1705 can directly match a reference impedance“ZL” for high frequency input and can force match an impendence of amultiple of the reference impedance, i.e., “M*ZL”, where “M” is thetotal number of cells in the row and the number of columns in thematrix, for low frequency input. In some implementations, global inputimpedance matching element 1705 can be implemented as a diplexer.

Each local impedance matching element 1715 is associated with arespective stack 110 and includes a control terminal output 1415 and amain terminal output 1420. Control terminal outputs 1415 are to becoupled to a respective control terminal of transistor 105 in theassociated stack 110. Main terminal outputs 1420 are to be coupled to arespective main terminal of the same transistor 105 in the associatedstack 110.

Column-to-column conductors 1710 and local impedance matching elements1715 together define portions of the signal from source 50 that areinput into each of the active cells 105. In some implementations, theconductors 1710 and impedance matching elements 1715 together define acharacteristic impedance of “ZL” at the end of the row (to the right inthe schematic representation of FIG. 17) and a characteristic impedanceof “ZL/k” for every active cell 105, where “k” is the position of thebottommost active cell 105 in bottom row 138 of the matrix. Thus, thefirst active cell 105 in the bottom row will have a characteristicimpedance of “ZL/M,” where “M” is the total number of cells in the rowand the number of columns in the matrix. In the implementation shown inFIG. 17, M is equal to 4. This implementation can be referred to as a“parallel line feed and match” topology.

As a result, at high frequencies, the input impedance at the beginningof the row is ZL/M. At low frequencies, the input impedance is ZL. Insome implementations, an additional matching network for highfrequencies can be used and the high-frequency input impedance can beraised, e.g., from ZL/M to ZL.

FIG. 18 is a schematic representation of a distribution line 130 andimpedance matching element 135 that can be coupled to distribute asignal from signal source 50 to a row of transistors 105. In theillustrated implementation, the row of transistors 105 into whichdistribution line 130 and impedance matching element 135 distribute asignal will be one of the higher rows of a matrix rather than a bottomrow. The illustrated implementation of distribution rail 115 includes acollection of column-to-column conductors 1810 and impedance matchingelements 1815.

Each impedance matching element 1815 is associated with a respectivestack 110 and includes a control terminal output 1415 and a mainterminal output 1420. Control terminal outputs 1415 are to be coupled toa respective control terminal of a transistor 105 in the associatedstack 110. Main terminal outputs 1420 are to be coupled to a respectivemain terminal of the same transistor 105 in the associated stack 110.

Column-to-column conductors 1810 connect impedance matching elements1815 (and hence the input paths of respectively associated transistors105) in series. In particular, a conductive path 1817 passes througheach of the impedance matching elements 1815 and the signals conductedalong conductive path 1817 return to signal source 50 via a return line1819. In the illustrated implementation, conductive path 1817 and returnline 1819 are separated by a capacitance 1825 that blocks DC signalsfrom returning to signal source 50. In other implementations, capacitor1825 can be omitted and conductive path 1817 and return line 1819 aredirectly connected.

Each impedance matching element 1815 couples a portion of the signal onconductive path 1817 into a respective transistor 105 in the associatedstack 110. The impedances presented by impedance matching elements 1815depend on the position of impedance matching elements 1815 alongconductive path 1817. In particular, the impedance matching element 1815at the end of conductive path 1817 (to the right in the illustratedrepresentation) presents a characteristic impedance of ZL/M, where M isthe number of columns in the matrix. Other impedance matching elements1815 present a characteristic impedance of “ZL/k,” where “k” is theposition of the impedance matching element 1815 along conductive path1817. In the illustrated representation, “k” is equal to one for theleftmost impedance matching element 1815, “k” is equal to two for theimpedance matching element 1815 that is second from the left, etc.Therefore, the impedance 1820 seen from the source 50 into the entirematching and distribution subcircuit 130, 135 is matched to ZL. As aresult, for the k^(th) transistor 105 in a row, the DC feed is providedthrough the series-connected “forced matching” impedances to the left ofthe k^(th) transistor 105. Accordingly, this implementation can bereferred to as a “series line feed and match” topology.

In some implementations, impedance matching elements 1815 areimplemented as diplexers or other structures that directly match theimpedance ZL/M at high frequencies or force a match at low frequencies.

FIG. 19 is a schematic representation of a distribution line 130 andimpedance matching element 135 that can be coupled to distribute asignal from signal source 50 to a row transistors 105. The illustratedimplementation of distribution line 130 and impedance matching element135 includes a collection of transformers 1905, column-to-columnconductors 1910, and impedance matching elements 1915.

Each impedance matching element 1915 is associated with a respectivestack 110 and includes a control terminal output 1415 and a mainterminal output 1420. Control terminal outputs 1415 are to be coupled toa respective control terminal of a transistor 105 in the associatedstack 110. Main terminal outputs 1420 are to be coupled to a respectivemain terminal of the same transistor 105 in the associated stack 110.

Transformers 1905 each include a first winding 1930 and a second winding1935. First windings 1930 and one of the conductors of column-to-columnconductors 1910 are coupled in series to form a conductive path 1917.The other of the conductors of column-to-column conductors 1910 arecoupled together to form a return line 1919. In the illustratedimplementation, conductive path 1917 and return line 1919 are separatedby a capacitance 1945 that blocks DC signals from returning to signalsource 50. In other implementations, capacitor 1825 can be omitted andconductive path 1917 and return line 1919 directly connected.Transformers 1905 enable a direct DC input feed for each active cell 105of the row even without the forced-matching serial resistances in theinput DC path (such as shown in FIG. 18).

In some implementations, the circuitry schematically represented in FIG.19 can also include a DC decoupling resistance, such as impedance 155(FIG. 1). In these cases, the circuitry can be used as a distributionrail 115 to distribute a signal from a signal source 50 to thebottommost transistors 105 in each of stacks 110. In some of theseimplementations, the source/emitter main terminals of the bottommosttransistors 105 can be coupled to ground rather than to main terminaloutput 1420.

FIG. 20 is a schematic representation of a distribution line 130 andimpedance matching element 135 that can be coupled to distribute signalsfrom pair of signal sources 50 a, 50 b to a row of transistors 105. Theillustrated implementation of distribution line 130 and impedancematching element 135 includes a collection of three-conductorcolumn-to-column conductors 2010 and impedance matching elements 2015.

In the illustrated implementation, signal sources 50 a, 50 b are amatched pair field effect transistors. A balanced control signal isinput into both control terminals 53 of signal sources 50 a, 50 b. Afirst main terminal of signal source 50 a (i.e., the drain terminal inthe illustrated implementation) is coupled to a first conductor 2020 ofcolumn-to-column conductors 2010. A first main terminal of signal source50 b (i.e., the drain terminal in the illustrated implementation) iscoupled to a second conductor 2025 of column-to-column conductors 2010.The third conductor 2030 of column-to-column conductors 2010 is a commonreturn line. One end of third conductor 2030 is coupled to each of thefirst main terminal of signal source 50 a and the first main terminal ofsignal source 50 b—as well as conductors 2020, 2025—by a respectiveresistance 2055. In the illustrated implementation, the other end ofthird conductor 2030 is coupled to each of conductors 2020, 2025 by arespective capacitance 2045 that blocks DC signals from returning tosignal sources 50 a, 50 b.

In each conductor 2020, 2025, alternate one of impedance matchingelements 2015 (and hence the respectively associated transistors 105)are coupled in series. In particular, conductor 2020 forms a conductivepath that passes through every other impedance matching element 2015(namely, the first and the third in the illustrated implementation).Conductor 2025 forms a conductive path that passes through every otherimpedance matching element 2015 (namely, the second and the fourth inthe illustrated implementation). Conductor 2020 thus distributes thedrive signal generated by signal source 50 a to one half of the activeelements 105 in the row, whereas conductor 2025 distributes the drivesignal generated by signal source 50 b to the other half of the activeelements 105 in the row.

As with the “series line feed and match” topology of FIG. 18, eachimpedance matching element 2015 couples a portion of the signal on therespective of conductors 2020, 2025 into a respective transistor 105 inthe associated stack 110. The impedances presented by impedance matchingelements 2015 depend on the position of impedance matching elements 2015along conductors 2020, 2025. In particular, the impedance matchingelement 2015 at the end of conductor 2020 (to the right in theillustrated representation) presents a characteristic impedance ofZL/M/2, where M is the total number of columns in the matrix. Otherimpedance matching elements 2015 present a characteristic impedance of“ZL/k,” where “k” is the position of the impedance matching element 2015along the respective of conductors 2020, 2025. In the illustratedrepresentation, “k” is equal to one for both the leftmost and thesecond-leftmost impedance matching elements 2015 since those impedancematching elements 2015 are along different of conductors 2020, 2025. Asa result, the DC feed is provided through a reduced number ofseries-connected “forced matching” impedances to the left of eachtransistor 105, hence reducing DC series feed resistance for eachindividual active cell. Accordingly, this implementation can be referredto as a “series line feed and match with full-symmetrical lines”topology.

Although the illustrated implementation of the “series line feed andmatch with full-symmetrical lines” topology is shown with two signalsources 50 a, 50 b and two conductor 2020, 2025, in otherimplementations, more than two signal sources and/or more than twoconductors can be used to provide a drive signal to the active cells 105in a single row.

FIG. 21 is a schematic representation of an unbalanced collection rail120 that is coupled to collect the signals passing through M columns ofa matrix power amplifier and direct them to a load 70. For the sake ofconvenience, only the uppermost row of transistors 105 of four stacks110 is illustrated. The illustrated implementation of collection rail120 includes a collection of column-to-column conductors 2105 andimpedance matching elements 2110.

Each impedance matching element 2110 is associated with a respectivestack 110 and, in the illustrated implementation, includes an inductance2115 and a capacitance 2120. The magnitude of the components formingmatching elements 2110 can be configured, e.g., to compensate for theeffective output capacitance of each respective stack 110. In otherimplementations, impedance matching elements 2110 can be omitted and theoutput of each respective stack 110 can be coupled directly torespective of column-to-column conductors 2105.

In the illustrated unbalanced implementation of a collection rail 120,each column-to-column conductor 2105 includes a grounded wire and anungrounded wire. The ungrounded wires are coupled in series and to theoutputs of stacks 110. In the illustrated orientation, the leftmostcolumn-to-column conductor 2105 has an impedance of N*ZL, where N is thenumber of rows in the matrix. Continuing from the left, the k^(th)column-to-column conductor 2105 has an impedance of N*ZL/k, where N isthe number of rows in the matrix, and the final N-th line has theimpedance N*ZL/M, where M is the number of columns in the matrix. Theline lengths of lines 2105 are dimensioned to match the delay betweeninput or output signals of adjacent stacks 110. For example, whenunbalanced collection rail 120 is used in a matrix amplifier inconjunction with a distribution line 130 and impedance matching element135 such as shown in FIG. 18, the line lengths of lines 2105 aredimensioned to match the delays associated with respective portions ofconductive path 1817. One terminus of the series-connected ungroundedwires is coupled to the combined port of high power bias tee 170. Thehigh frequency port of bias tee 170 is coupled to load 70 and the lowfrequency port is coupled to DC source 160. The ungrounded wires arethus biased by DC source 160 which supplies the “matrix drain/collectorvoltage” (i.e., the number of rows N times the drain/collector voltageof the individual cells or N*VDD) to the individual cells of the top rowvia the series-connected ungrounded wires of collection rail 120. Theload resistance value is RL=N/M*R_Cripps, and the reference impedancevalue ZL is equal to the load resistance value RL. “R_Cripps” is theoptimum load resistance of the individual FET/BJT cell—either for power,or power-added efficiency, or some compromise therebetween.

In the illustrated implementation, the top active cell in one stack 110includes an output prematch network 2130. Output prematch network 2130is an optional component and, in general, will be deployed for eitherthe top active cell in every stack 110 of the matrix amplifier or forevery cell of the matrix amplifier. Each output prematch network 2130 isconfigured to match the output of a respective cell in the matrix to theimpedance seen by that cell so that the power output is high and a highpower added efficiency is achieved. In general, it is desirable that thepower added efficiency is as high as possible. In the context of acollection rail 120, each output prematch network 2130 on the top activecell of the stack 110 is configured to match the impedance seen by thatcell on collection rail 120. This implementation of collection rail 120can be referred to as a “special” non-uniform distributed poweramplifier (NDPA) topology. In particular, the illustrated implementationof collection rail 120 is “special” in that all active cells haveapproximately the same cell size, which contrasts with classical NDPA inwhich cell size varies to improve matching. In the special NDPA, nearlyequal active cell sizes are possible because the characteristicimpedances of the output lines are divided by the stacking factor N.Since the active cell sizes are nearly equal, implementation in planarintegrated technology is facilitated.

FIGS. 22 and 23 are schematic representations of a pair of rows 137within a matrix power amplifier. Distribution lines 130 are coupled tothe control terminals of the transistors 105 in each row 137. Althoughonly a pair of rows 137 and a single distribution line 130 areillustrated, a complete matrix power amplifier can have severaladditional rows and distribution lines.

The illustrated distribution line 130 is implemented as a balanced twoconductor transmission-line and includes a control signal line 2205 anda main signal line 2210. Control signal line 2205 is coupled todistribute some portion of a drive signal to each of the controlterminals of the transistors 105 in a respective row 137. In theimplementation illustrated in FIG. 22, the drive signal is coupleddirectly to the control terminals by a conductor 2215. In theimplementation illustrated in FIG. 23, the drive signal is coupled viaan impedance matching element 2305. The delays associated with portionsof control signal line 2205 and either conductors 2215 or impedancematching element 2305 can be chosen to coordinate current conduction bytransistors 105 in the respective row 137.

Main signal line 2210 is coupled to the main terminals of transistors105 in both the same row 137 that receives drive signals from controlsignal line 2205 and the preceding row 137. In particular, main signalline 2210 is coupled to the source or emitter terminal of thetransistors 105 in the same row 137 that receives drive signals fromcontrol signal line 2205 and the drain or collector of the transistors105 in the preceding row 137. As a result, main signal line 2210combines the outputs of the drain or collector terminals of thetransistors 105 in one row 137 and divides the result amongst the sourceor emitter terminals of the transistors 105 in the next row 137.

In the implementation illustrated in FIG. 22, main signal line 2210includes a group of stack-to-stack conductors 2220 that couple to the(as illustrated, vertical) conductors between the main terminals oftransistors 105 in adjacent rows 137. In the implementation illustratedin FIG. 23, main signal line 2210 includes a group of impedance matchingelements 2310 that couple to a position between an unbalanced impedancematching element 2315 that couples to the drain or collector of thetransistors 105 in the preceding row 137 and impedance matching element2305—which couples to the source or emitter terminal of the transistors105 in the same row 137 that receives drive signals from control signalline 2205. In other implementations, the conductors between the mainterminals of individual transistors 105 in adjacent rows 137 can bereplaced by combiner/divider elements that combine the signals on thedrain or collector terminals of the transistors 105 in one row 137 andthen divides the resultant signal amongst the source or emitterterminals of the transistors 105 in the next row 137.

By combining the outputs of transistors 105 in one row 137 and thendividing the result amongst the transistors 105 in the next row 137,conduction within the matrix amplifier can be balanced. In particular,the resulting matrix amplifier has an orthogonal row and columninterconnection scheme where the input control signal is fed via lines2205 in row-direction and the output signals of the individualtransistors 105 are collected or transferred via lines 2215 (or,alternatively in FIG. 23, via matching elements 2305 and 2315) from onerow of active cells to the next.

In the implementation illustrated in FIG. 22, main signal line 2210 isbias by an optional DC source 2225 that is coupled to main signal line2210 via an inductance 2230. DC source 2225 can bias main signal line2210 to a potential that is a fraction of the potential supplied by DCsource 160 to collection rail 120. In particular, DC source 2225 canbias the k^(th) row 137 with a potential equal to k/N of that suppliedby DC source 160, where N is the total number of rows. By coupling DCsource 2225 to main signal line 2210, DC source 160 need not supplypower to the entire matrix amplifier. Rather, the DC drain biasing canbe split in a partly or fully row-wise manner, allowing the multiplesmaller sources to supply that power.

FIG. 24 is a schematic representation of a matrix power amplifier 2400.Matrix power amplifier 2400 includes a single active matrix driver 125that drives multiple stacks 110. Stacks 110 are themselves coupled inparallel between unbalanced distribution rail 115 and unbalancedcollection rail 120. Distribution rail 115 is coupled to distribute asignal from a signal source 50 to the bottommost transistors 105 in eachof stacks 110. Collection rail 120 is coupled to collect the signalspassing through stacks and direct them to a load 70. DC source 160 iscoupled to bias all stacks 110.

Active matrix driver 125 drives each of rows 137 separately using arespective row distribution line 130. Row distribution line 130terminates in a real impedance 1310 and a capacitive impedance 1315. Thevalues of impedances 1310, 1315 are configured to match the impedance ofrow distribution line 130 so that a drive signal is appropriatelycoupled thereto from matrix driver 125. In particular, capacitor 1315 isused for DC separation between the input control voltage and the outputterminal voltage, while the resistor 1310 is set to match thecharacteristic impedance of the lines 130.

FIG. 25 is a schematic representation of a matrix power amplifier 2500.Matrix power amplifier 2500 does not include an active matrix driver125. Rather, each stack 110 includes a parallel or serial“bootstrapping” driver such as illustrated, e.g., in FIGS. 4, 5, 6, and8. In these implementations, distribution rail 115 is coupled todistribute the signal from signal source 50 to the transistors 105 inthe bottommost row 138. The resultant potential on the drain orcollector of the transistors 105 in row 138 is bootstrapped to bias thecontrol terminals of transistors 105 in succeeding rows 137, leading toa wave of current control passing through the two-dimensional matrix oftransistors 105 from the bottom to the top in the illustrated directionof the stacks 110. DC source 160 is coupled to bias all stacks 110.

FIG. 26 is a schematic representation of a matrix power amplifier 2600.Matrix power amplifier 2600 includes a multiple active matrix drivers125 that each drives multiple stacks 110. Each stack 110 is formed by acollection of active cells coupled in series between distribution rail115 and collection rail 120. However, in the illustrated implementation,each active cell is formed by a pair of transistors 105 that areparalleled. In particular, the control terminals of both transistors inthe pair are coupled together and receive a single control signal.Further, respective main terminals of both transistors are coupled, ineffect doubling the current-carrying capacity of the active cells bydoubling the active area of the active cells. Thus, in the illustrativeschematic representation, each active matrix driver 125 drives a pair ofstacks 110, one illustratively disposed to the left of the active matrixdriver 125 and one illustratively disposed to the right of the activematrix driver 125.

In some implementations, the main terminals of active cells that aredriven by different active matrix drivers 125 can be coupled together tocombine the outputs of transistors 105 driven by different active matrixdrivers 125. The resulting signal can then be divided amongst thetransistors 105 in the next row. An example of such an approach is shownin FIGS. 22, 23, albeit in the context of one transistor 105 per activecell.

FIG. 27 is a schematic representation of a matrix power amplifier 2700.Matrix power amplifier 2700 includes multiple unbalanced passive matrixdrivers 305. In the illustrated implementation, each unbalanced passivematrix driver 305 is coupled to an active cell that includes multipletransistors 105 by a balun transformer 315. Balun transformers 315 bothconvert the unbalanced signal on passive matrix drivers 305 to balancedsignals and act as impedance matching elements to couple the drivesignals to transistors 105 in different stacks 110.

In the illustrated implementation, the main terminals of active cellsthat are driven by different passive matrix drivers 305 are coupledtogether to combine the outputs of transistors 105 driven by differentpassive matrix drivers 305. The resulting signal is then divided amongstthe transistors 105 in the next row.

In the illustrated implementation, two of the unbalanced passive matrixdrivers 305 (i.e., the passive matrix drivers 305 disposed in the middleof the schematic representation) shared a single grounded return line.This is not necessarily the case. For example, in some implementations,each passive matrix drivers 305 can include an individual return line.

In the illustrated implementation, two of the unbalanced passive matrixdrivers 305 (i.e., the passive matrix drivers 305 disposed to the leftand to the right in the schematic representation) have individualgrounded return line. This is not necessarily the case. For example, insome implementations, these two passive matrix drivers 305 can alsoshare a single return line.

FIGS. 28, 29 are schematic representations of matrix power amplifiers2800, 2900. Matrix power amplifiers 2800, 2900 are both examples of“non-square” matrix in that the number of columns M is not equal to thenumber of rows N in the matrix. In some implementations, this mayfacilitate matching the impedance of the active cells in the matrix tothe impedance of an external system load (e.g., using the Crippsload-line method).

In some implementations, matrix power amplifiers 2800, 2900 may includean active matrix driver 125. In some such implementations, the size orother characteristics of such an active matrix driver 125 may differfrom the size or other characteristics of the active cells in thematrix. In such implementations, the power of the signal output bysignal source 50 will not be identically distributed to the activematrix driver 125 and each of the active cells in the bottom row 138 ofthe matrix. Equations 4, 5 above can be adjusted to account for thisnon-uniform distribution.

FIG. 30a is a schematic representation of a matrix power amplifier 3000.Matrix power amplifier 3000 includes a parallel—connected plurality ofactive cells 3005 each of which is formed by multiple transistors 105.In particular, in the illustrated implementation, each active cell 3005includes three transistors 105. The control terminals and source/emittermain terminals of these transistors 105 are coupled to an active celldistribution line 3050 that couples portions of a drive signal to thecontrol terminals with appropriate delays to coordinate currentconduction by transistors 105. However, the drain/collector mainterminals of transistors 105 in each active cell 3005 are coupled to acollection line 3010 that collects the currents conducted between themain terminals of each transistor 105 in an active cell 3005. Collectionline 3010 conveys the currents collected from the drain/collector mainterminals of the transistors 105 in one active cell 3005 through anunbalanced line 3015 to the source/emitter main terminals of thetransistors 105 in the next active cell 3005 via the active celldistribution line 3050 of that next active cell 3005.

Active cell distribution lines 3050 receive the currents collected fromthe drain/collector main terminals of the transistors 105 in one activecell 3005 on one end (to the right in the illustrated orientation) andconvey those currents to the source/emitter main terminals of thetransistors 105 in the associated active cell 3005 as to a thenon-inverting terminal of impedance-matching differential amplifier 3055in a matrix driver 125. The lines that form each active celldistribution line 3050 are dimensioned so that the input capacitances oftransistors 105 are hidden in the cell distribution line 3050 like in adistributed amplifier (TWA) and the output of baluns 3055 is matched tothe active cells. Further, the output collection line is dimensionedlike in a non-uniform distributed power amplifier (NDPA) with regard tosignal timing and the load impedance which is seen by each transistor105 in row 3005.

In the illustrated implementation, matrix driver 125 includes not onlythe differential amplifiers 3055 between active cells 3005, but also aresistive voltage divider chain 168 which is connected to FETs acting assource followers or voltage sources, respectively, which set the correctDC biasing voltages for the differential amplifiers 3055.

FIG. 30b is a schematic representation of an impedance-matchingdifferential amplifier 3055 that can be used in row-matched matrix poweramplifiers. Differential amplifier 3055 includes an inverting inputterminal 3180, a non-inverting input terminal 3182, a high outputterminal 3184, and a low output terminal 3186. Differential amplifier3055 also includes a high supply terminal 3190 and a low supply terminal3192.

Differential amplifier 3055 includes a pair of matched transistors 3194that each are coupled between a high drain-side potential and a lowsource-side potential. The control terminal of the first of transistors3194 is coupled to non-inverting input terminal 3182. The controlterminal of the second of transistors 3194 is coupled to inverting inputterminal 3180. Differences in the potential at input terminals 3180,3182 result in differences in the conductivity of transistors 3194.Those differences in the conductivity of transistors 3194 result indifferent potential drops across impedances 3196, 3197 that couple thedrains of transistors 3194 to high supply terminal 3190. Outputterminals 3184, 3186 output the resulting difference.

As shown, the sources of transistors 3194 are coupled together and sharea common path to low supply terminal 3192. The impedance between bothoutput terminals 3184, 3186 and low supply terminal 3192 is thus nearlyidentical except for the relatively small differences in the impedanceof transistors 3194. Differential amplifier 3055 can thus act as a balunand convert an unbalanced input on inputs 3180, 3182 into a balancedoutput on output terminals 3184, 3186.

FIG. 31 is a schematic representation of a matrix power amplifier 3100.Like matrix power amplifier 3000 (FIG. 30a ), matrix power amplifier3100 also includes a collection of active cells 3005 formed by multipletransistors 105 and a collection line 3010 that conveys currentscollected from the drain/collector main terminals of those transistors105 to the source/emitter main terminals of the transistors 105 in thenext active cell 3005.

In matrix power amplifier 3100, matrix driver 125 receives the RF signaloutput by signal source 50 on an unbalanced distribution line 3105. Viaa series of transformers 3110, unbalanced distribution line 3105 couplesthe RF signal into the input terminals of differential amplifiers thatact as active impedance matching elements 135 to match the impedance ofthe active cell distribution lines 3050 and transistors 105.

FIG. 32 is a schematic representation of a two-dimensional matrix poweramplifier 3200. Two-dimensional matrix power amplifier 3200 includes ap-type two-dimensional matrix 3205 and an n-type two-dimensional matrix3210. P-type two-dimensional matrix 3205 includes a collection of p-typetransistors 105 that act as active elements. N-type two-dimensionalmatrix 3210 includes a collection of n-type transistors 105 that act asactive elements. A DC source 145 that outputs a DC signal which isnegative with respect to ground controls the current flow through N-typetwo-dimensional matrix 3210. A DC source 145 that outputs a DC signalwhich is positive with respect to ground controls the current flowthrough P-type two-dimensional matrix 3205. The RF signal that is outputby RF source 50 is level shifted by respective level shifting circuitry3215, 3220 that includes source followers and current sources (e.g.,formed of npn and pnp bipolar junction transistors, respectively) and DClevel shifting resistors therebetween for coupling to respective ofmatrices 3205, 3210.

Two-dimensional matrix power amplifier 3200 thus provides load 70 with a“DC-free” RF output referenced to ground or zero potential.

FIG. 33 is a schematic representation of a two-dimensional matrix poweramplifier 3200 that includes a pair of p-type two-dimensional matrices3205 and n-type two-dimensional matrices 3210 assembled into a “full-H”configuration. Two-dimensional matrix power amplifier 3200 provides asymmetric RF output which is required (e.g. for output to a Lecher-typeantenna feeder).

FIG. 34 is a schematic representation of a matrix power amplifier 3400.Matrix power amplifier 3400 includes a parallel-connected plurality ofactive cells 3005 each of which includes four transistors 105.

In contrast with matrix power amplifiers 3000, 3100 (FIGS. 30, 31),matrix power amplifier 3400 includes biasing circuitry 3405 that iscoupled between active cells 3005. Biasing circuitry 3405 biases thecollection line 3010 of one active cell 3005 via unbalanced line 3015and the line of the active cell distribution line 3050 that is coupledto the source/emitter main terminals of the transistors 105 in theadjacent active cell 3005. In other words, biasing circuitry 3405 biasesboth the output from the main terminals 105 of the transistors oneactive cell 3005 and the input of the main terminals of the transistors105 in the adjacent active cell 3005.

As a result, any DC current conducted between the control terminals andthe source/emitter main terminals of the transistors 105 is not re-used.This lowers the output DC supply voltage by a factor N equal to thenumber of rows, but increases the total required DC supply current bythe same factor N relative to the other topology variants presentedherein. Nevertheless, the total RF output voltage and current swing inmatrix amplifier 3400 are substantially the same as in these othervariants.

FIG. 35 is a schematic representation of a matrix power amplifier 3400.Matrix power amplifier 3500 that includes a two-dimensional matrix oftwo-dimensional matrix of matrix power amplifiers. The matrix poweramplifiers in matrix power amplifier 3500 can be any of the matrix poweramplifiers 100, 200, . . . described herein. In some implementations,the matrix power amplifiers in matrix power amplifier 3500 can beinterconnected using transmission line interconnects that haverelatively large cross-sections using hybrid integration ormulti-chip-module assembly technologies instead of monolithic microwaveintegrated circuits. Further, the combining losses can be maintained lowenough for effective power combining. With such a matrix of matrix poweramplifiers, the total output power can be further increased whilemaintaining a desired impedance matching.

FIG. 36 is a schematic representation of a push-pull stage 3600 thatincludes a pair of matrix amplifiers 3605, 3610. In the illustratedimplementation, each of matrix amplifiers 3605, 3610 includes a singlestack of transistors 105 that are bootstrapped together so that thesignal output on a main terminal of one transistor 105 drives thecontrol terminal of the subsequent transistor 105. In otherimplementations, matrix amplifiers 3605, 3610 can include multiple suchstacks and/or distribute the drive signal using any of the circuitsdescribed herein.

Matrix amplifiers 3605, 3610 are coupled together to form push-pullstage 3600. In push-pull stage 3600, current flow though matrixamplifier 3610 acts to “pull up” collection rail 120 to a positivepotential relative to ground defined by DC source 3615. Current flowthough matrix amplifier 3605 acts to “push down” collection rail 120 toa negative potential relative to ground defined by DC source 3612.

The illustrated implementation of push-pull stage 3600 also includes across-amplifier bootstrapping transistor 3620, resistances 3652, 3654,capacitance 3658, and inductance 3659. In particular, transistor 3620and these components together bootstrap the signal output on collectionrail 120 so that the control terminal(s) of the transistor(s) 3625 inthe bottom row of matrix amplifier 3610 switch those transistor(s) 3625into conduction. The signals output on the main terminal oftransistor(s) 3625 drives the control terminal of the transistor(s) inthe next row, and the drive signal propagates through the matrix ofmatrix amplifier 3610 until current flow though matrix amplifier 3610acts to “pull up” collection rail 120.

Collection rail 120 is coupled to collect the signals passing throughboth matrix amplifiers 3605, 3610 and couple them to load 70. In theillustrated implementation, an output impedance matching network 3630 iscoupled between collection rail 120 and load 70 to improve the powertransfer. Since there is no bias tee disposed between collection rail120 and load 70, the current limits and (especially, low) frequencyperformance limits of bias tees can be avoided.

Further, push-pull stage 3600 includes a low-frequency control loop thatregulates the DC potential on collection rail 120. As a result of thisregulation, the output of push-pull stage 3600 is DC-free, i.e.,symmetrical to the positive and negative DC supply voltages supplied byDC supplies 3612, 3615. The control loop includes an error amplifier3640 and employs matrix amplifier 3610 as a controller to regulate theoutput of push-pull stage 3600. Error amplifier 3640 is a low-frequencyor quasi-DC differential amplifier that is coupled to determine the lowfrequency differences between the potential on output rail 120 andground and output the difference as an error signal on conductor 3660.The frequency response of error amplifier 3640, including the uppercut-off frequency, is determined by a collection of resistive andcapacitive elements 3661, 3662, 3663, 3665, 3666. The error signal iscoupled by a conductor 3660 to the control terminal(s) of thetransistor(s) 3625 in the bottom row of matrix amplifier 3610.Transistor(s) 3625 responds to the error signal as a source follower andadjusts the DC potential on output rail 120 to zero.

The illustrated push-pull stage 3600 can be designated as an “activesource follower return.” In particular, matrix amplifier 3605 can beconsidered to be a “common source amplifier” with a source terminalcoupled to the negative potential relative to ground, the controlterminal coupled to RF source 50, and the drain coupled to the outputcollection rail 120 and to ground via a collection of real impedances3650, 3652, 3654 and capacitances 3656, 3658. Also, matrix amplifier3610 can be considered an “active return” for the source follower ofmatrix amplifier 3605. In particular, matrix amplifier 3610 activelyreturns output collection rail 120 to a higher potential by conductingcurrent from DC source 3615 in response to the drive signal bootstrappedvia cross-amplifier bootstrapping transistor 3620.

FIG. 37 is a schematic representation of a push-pull stage 3700 thatincludes a pair of matrix amplifiers 3705, 3710. In the illustratedimplementation, each of matrix amplifiers 3705, 3710 includes a singlestack of transistors 105 that are driven by a respective chain of activebaluns or differential amplifiers 3715 and 3720 or 3725 and 3730. Eachdifferential amplifier 3715, 3720, 3725, 3730 includes a pair oftransistors and amplifies the difference between the potentials on theirrespective control terminals to drive a transistor 105 of an active cellof the matrix amplifier.

For example, in matrix amplifier 3705, bottommost differential amplifier3715 amplifies a portion of the signal from signal source 50 that iscoupled not only to the control terminals of the transistors inbottommost differential amplifier 3715 but also to the control terminalof the transistor 105 in the bottom row of matrix amplifier 3705. Theupper main terminal (e.g., drain/collector) of one of the transistors inbottommost differential amplifier 3715 (the left transistor in theillustrated representation) is coupled not only to the control terminalof one the transistors in the subsequent differential amplifier 3720(the right transistor in the illustrated representation) but also to thecontrol terminal of the transistor 105 in the subsequent row or activeelements The control terminal of the other transistor in this samedifferential amplifier 3720 is coupled to the upper main terminal (e.g.,drain/collector) of the transistor 105 in the bottom row. Thedifferences in the biases applied to the control terminals of thetransistors forming each differential amplifier 3720 likewise propagateto a subsequent differential amplifier 3720 and the conductivity of thetransistors 105 in matrix amplifier 3705 is controlled in concert.

Please note that the control terminals of the transistors indifferential amplifier 3720 are always coupled to the same of the mainand control terminal of the associated transistor 105. In other words,the inverting input of each differential amplifier 3720 is alwayscoupled to one of the main and control terminal of the associatedtransistor 105, and the non-inverting input of each differentialamplifier 3720 is always coupled to the other.

In matrix amplifier 3710, bottommost differential amplifier 3725 ineffect amplifies the signal from signal source 50 with an oppositepolarity so that current conduction through matrix amplifier 3710 isincreased and decreased in anti-phase with the increases and decreasesin current conduction through matrix amplifier 3705. This is achieved byreversing the couplings between the inverting and non-inverting inputsof differential amplifiers 3725, 3730 and the main and control terminalof the associated transistors 105. As a result, the differences in thebiases applied to the control terminals of the transistors formingmatrix amplifier 3710 are in anti-phase with the differences in matrixamplifier 3705.

Matrix amplifiers 3705, 3710 are thus coupled together to form push-pullstage 3700. In push-pull stage 3600, current flow though matrixamplifier 3710 acts to “pull up” collection rail 120 to a positivepotential relative to ground defined by DC source 3615. Current flowthough matrix amplifier 3705 acts to “push down” collection rail 120 toa negative potential relative to ground.

The illustrated push-pull stage 3700 can also be designated as a “commonsource amplifier.” In other implementations, each of matrix amplifiers3705, 3710 can include multiple stacks of transistors 105.

Further, push-pull stage 3700 includes low-frequency control loops thateach regulates the DC potential on a respective collection rail 120. Asa result of this regulation, the output of push-pull stage 3700 isDC-free, i.e., symmetrical to the positive and negative DC supplyvoltages supplied by DC supplies 3612, 3615. The control loop includesan error amplifier 3640 and employs matrix amplifier 3710 as acontroller to regulate the output of push-pull stage 3700. Erroramplifier 3640 is a low-frequency or quasi-DC differential amplifierthat is coupled to determine the low frequency differences between thepotential on output rail 120 and ground. This error signal is coupled byconductor 3660 to the bottommost differential amplifier 3725. Bottommostdifferential amplifier 3725 and the associated transistor 105 adjust theDC potential on output rail 120 to zero.

FIG. 38 is a schematic representation of a two-dimensional matrix poweramplifier 3800 that includes a pair of push-pull stages 3802, 3804coupled in an “H-type” configuration to provide a symmetric RF output(e.g. for output to a Lecher-type antenna feeder).

In particular, push-pull stage 3802 includes a pair of matrix amplifiers3805, 3810. Push-pull stage 3804 includes a pair of matrix amplifiers3815, 3820. In the illustrated implementation, each of matrix amplifiers3805, 3810, 3815, 3820 includes a single stack of transistors 105 thatare bootstrapped together so that the signal output on a main terminalof one transistor 105 drives the control terminal of the subsequenttransistor 105. In other implementations, matrix amplifiers 3805, 3810,3815, 3820 can include multiple such stacks and/or distribute the drivesignal using any of the circuits described herein.

Each push-pull stage 3802, 3804 also includes a cross-amplifierbootstrapping transistor 3620 and one or more associated resistances,capacitances, and or inductances. Each transistor 3620 and theassociated components together bootstrap the signal output on arespective collection rail 120 so that the control terminal(s) of thetransistor(s) in the bottom row of the respective of matrix amplifiers3810, 3820 switch those transistor(s) into conduction. The signalsoutput on the main terminal of transistor(s) is in turn bootstrapped therespective of matrix amplifiers 3810, 3820.

The push signals passing through matrix amplifier 3805 and the pullsignals passing through matrix amplifier 3810 are collected by acollection rail 120 and directed to a first terminal 3870 of load 70.Also, the push signals passing through matrix amplifier 3815 and thepull signals passing through matrix amplifier 3820 are collected by acollection rail 120 and directed to a second terminal 3875 of load 70.These signals are 180 degrees out of phase so that load 70 is drive witha symmetric RF output.

Further, matrix power amplifier 3800 includes a pair of low-frequencycontrol loops that each regulates the DC potential on a respectivecollection rail 120. As a result of this regulation, the output ofpush-pull stages 3802 and 3804 is DC-free, i.e., symmetrical to thepositive and negative DC supply voltages supplied by DC supplies 3612,3615. The control loops each include an error amplifier 3640 and employsa respective of matrix amplifiers 3810, 3820 as a controller to regulatethe output of matrix power amplifier 3800. Error amplifiers 3640 arelow-frequency or quasi-DC differential amplifiers that are each coupledto determine the low frequency differences between the potential on arespective output rail 120 and ground. This error signal is coupled by arespective conductor 3660 (denoted “A” for push-pull stage 3802 and “B”for push-pull stage 3804) to the control terminal(s) of the bottommosttransistor(s) 105 in the respective of matrix amplifiers 3810, 3820.These bottommost transistor(s) 105 adjust the DC potential on therespective output rail 120 to zero.

FIG. 39 is a schematic representation of a push-pull stage 3900 thatincludes a pair of matrix amplifiers 3905, 3910. In the illustratedimplementation, each of matrix amplifiers 3905, 3910 includes fourstacks 110 of transistors. The transistors in each row in both matrixamplifiers 3905, 3910 are driven by distribution line 130 and arespective impedance matching element 135. In the illustratedimplementation, impedance matching elements 135 are shown as activedriver amplifiers.

As shown, the input polarity of the active driver amplifiers in thematching elements 135 of matrix amplifier 3905 is the reverse of theinput polarity of the active driver amplifiers in the matching elements135 of matrix amplifier 3910. As a result, the active cells in matrixamplifier 3905 are driven in anti-phase with the active cells in thetwo-dimensional matrix 3910.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made. For example, theparallel bootstrap driver topology used in the columns of a matrixamplifier (e.g., in FIGS. 4, 5 and in the push-pull matrix amplifiers ofFIGS. 36, 38) can be used in conjunction with an active column driverstage. In such cases, the voltage divider of the parallel bootstrapdriver is connected to a transistor in the active driver rather than totransistors 105 in the active cells.

Accordingly, other implementations are within the scope of the followingclaims.

What is claimed is:
 1. A power amplifier comprising: an amplifier inputand an amplifier output; a plurality of N times M active cells, whereinN and M are both ≥2 and the active cells are wired as a M×N matrix; andat least one driver structure to drive the active cells; wherein one ofa), b), or c) applies, wherein: when a) applies, the matrix columns eachinclude N active cells coupled in series and driven as a stack, whereinthe stacks are coupled in parallel, when b) applies, the matrix rowseach include M active cells coupled to be driven in parallel, wherein atleast two matrix rows are coupled in series, and when c) applies, thematrix columns each include N active cells coupled in series and drivenas a stack, wherein the stacks are coupled in parallel and the matrixrows each include M active cells coupled to be driven in parallel,wherein at least two matrix rows are coupled in series; wherein acontrol terminal of each active cell is coupled to the amplifier inputvia a signal path that includes the driver input structure, wherein theactive cells are all controllable by an electrical signal input to theamplifier input.